The History of Telephone Exchanges – The World and Romania

📖 Chapter I – The First Manual Telephone Exchanges (1878–1890)

1.1. Historical context of the appearance of the telephone

The invention of the telephone in the mid-nineteenth century fundamentally changed the way people communicated. Until then, the telegraph had been the main instrument for the rapid transmission of information at a distance. However, the telegraph required knowledge of Morse code and involved a form of intermediation: the message was written, transmitted by electrical impulses, and then decoded at the destination.

Alexander Graham Bell's telephone (1876), but also the prototypes developed by Elisha Gray and other inventors, brought a revolution: the possibility of transmitting the human voice in real time, without complicated decoding. This innovation immediately created a new problem: how do we connect subscribers with each other?

In the beginning, the first phones were connected point to point: a wire directly connected two locations. But as the number of subscribers grew, this system became unmanageable: for 10 subscribers 45 direct links were needed, for 100 subscribers – 4950 links! The need for a centralized infrastructure was obvious.

This is how the concept of a telephone exchange appeared.

1.2. The World's First Telephone Exchange (1878)

Just two years after Bell's patent, in 1878, in the city of New Haven, Connecticut (USA), the first telephone exchange was put into operation.

This could connect about 21 subscribers.
The connections were made manually, by human operators, by means of a panel with cords and sockets.
Each subscriber was connected to the central bank through a dedicated wire.

The procedure was as follows: the subscriber lifted the receiver and the telephone crank generated a sound or light signal in the switchboard. The operator would answer and ask, "Who do you want to talk to?" Then manually connect the corresponding cord between the caller's line and the caller's line.

This simple but effective method was the basis of the first decades of organized telephony.

1.3. Role of human operators

In the era of manual boilers, operators were indispensable. Generally, companies hired young women for this work, who were considered more attentive, polite, and more resistant to repetitive load.

The operators were working on huge panels, with hundreds of sockets and cords.
They had not only a technical role, but also a social one: they had to be polite, quick and attentive to the confidentiality of calls.
In some cases, the operators knew the subscribers and could facilitate communication even without numbers (e.g. "Connect me with Dr. Popescu").

This human dimension has made the plant not only a technical equipment, but also a social node.

1.4. Expansion of manual telephone exchanges in the world

After 1878, manual boilers expanded rapidly:

USA: By 1880, there were already dozens of power plants in major cities.
Europe: the first power plants appear in London (1879), Paris (1880) and Berlin (1881).
Asia: Japan adopts telephony in 1890, also with manual switchboards.

These exchanges were, at first, small (20–50 subscribers), but within a few decades they ended up serving thousands of users.

1.5. The first telephone exchanges in Romania

Romania entered the telephony era relatively early.

1881: Bucharest already had the first private telephone lines, used mainly by institutions and commercial companies.
1883–1884: The first small-capacity manual boilers are installed, serving several dozen subscribers.
1890: It is estimated that there were several hundred telephones throughout the country, most of them in Bucharest, Iasi and Galati.

The plants were operated by trained personnel, and the service was expensive, addressed to urban elites and state institutions.

1.6. Problems and limitations of manual telephone exchanges

Although innovative, manual boilers had major limitations:

Reduced capacity: each operator could only handle a limited number of simultaneous calls.
Delays: At peak times, subscribers waited minutes until they were connected.
Reduced privacy: Operators could hear conversations.
Intense human effort: for a plant with thousands of subscribers, dozens or hundreds of operators were needed.

These problems have led inventors to look for automated solutions.

1.7. Social and cultural impact

The telephone and manual switchboards have had a huge impact:

Urbanization: Major cities have become better connected.
Commerce: Business has accelerated thanks to fast communication.
Social life: people were able to communicate remotely in real time, reducing isolation.
Luxury image: in Romania, the telephone was a symbol of modernity and prosperity.

1.8. Conclusions for the period 1878–1890

The period of manual switchboards laid the foundations of modern telephony.

He demonstrated the usefulness of the telephone as a public service.
He created the first telephone companies.
It revealed the limits of manual technology, paving the way for automation.

📖 Chapter II – The Strowger Age and Step-by-Step Switching (1891–1930)

2.1. The problem of operators and the context of the invention

By the 1880s and 1890s, manual boilers had already become crowded and full of shortcomings. Operators were overloaded, subscribers were frustrated with wait times, and conversation privacy was a constant issue. In addition, human errors were common: calls reached the wrong subscribers or were dropped.

In this context, an American entrepreneur from Kansas City, Almon Brown Strowger, radically changed the paradigm.

2.2. Who was Almon B. Strowger?

Born: 1839, in Penfield, New York.
Prophecy: director of undertaker.
Personal problem: he noticed that telephone operators were intentionally directing calls to a competitor (it is said that a relative of the operator worked for a rival firm).
Motivation: "My car needs to eliminate the operator between me and my customer."

In 1889, Strowger began work on a system that would allow calls to be switched automatically without operator intervention.

2.3. Patent and first prototype

Patent: filed in 1891 and granted in 1892.
New: an electromechanical system that allowed the automatic selection of the called line by means of a step-by-step selector.
Operation: the subscriber dials the desired number by pressing some buttons (later via the rotating telephone dial).

The first prototype was installed in La Porte, Indiana, in 1892. It was the world's first commercial automatic power plant.

2.4. Technical "step-by-step" principle

The Strowger selector worked in a step-by-step motion:

an electromagnetic mechanism moved the contact vertically (number of tens) and then horizontally (number of units);
Each press or pulse transmitted by the phone's dial moves the dial one step.
The combination of these steps led to the connection of the desired line.

Advantages:

completely eliminates the operator;
allow for an increase in the number of subscribers;
decrease the connection time.

Disadvantages:

the equipment was noisy;
maintenance requires specialized personnel;
Calls were limited in speed and quality compared to future systems.

2.5. International expansion (1890–1930)

United States

After the success of La Porte, the Strowger power plants expanded rapidly. By the 1910s, major American cities already had thousands of subscribers automatically connected.

Europe

Great Britain: the first implementations in 1912, with London gradually adopting the automatic system.
Germany: experimented with and implemented Strowger systems and other competing technologies.
France: timid beginnings, with more consistent implementations only after 1920.

Asia and other regions

Japan: adopts Strowger technology in the 1920s.
Latin America: cities like Buenos Aires and Rio de Janeiro install automatic control panels in the 1920s.

2.6. Situation in Romania

In Romania, the period 1890–1930 was one of transition from manual to automatic.

1890–1910: Boilers were still manual, but the first discussions about automation appeared.
1920–1930: in the big cities (Bucharest, Cluj, Timișoara) the installation of automatic Strowger power plants begins.
1930: The Romanian Telephone Company (SART) is established, associated with ITT, which will rapidly modernize the infrastructure and expand the automatic control panels.

Thus, Romania has entered the modern era of telephony along with the rest of Europe, albeit with a slight delay.

2.7. Economic and social impact

The introduction of automatic control units had profound consequences:

Decrease in dependence on operators: thousands of jobs have been affected, but the service has become faster and safer.
Increased public trust: Calls were more confidential.
Wider access: lower operating costs have allowed tariffs to fall.
Urbanization: large urban centers have become increasingly interconnected, supporting economic development.

2.8. Criticism and resistance

Not everyone was thrilled with the new system:

Many feared the loss of operators' jobs.
Some users found the system more complicated, especially when they had to learn to use the phone dial.
Telephone companies have invested huge amounts in the technological transition, which has generated political and financial controversies.

2.9. Conclusions for the Strowger era

Between 1891 and 1930, telephony went through the first great technical revolution:

call automation, eliminating the human operator;
scalability of the service, the possibility of connecting tens of thousands of subscribers;
a new technological standard, which dominated the first decades of the twentieth century.

Although noisy and mechanical, the Strowger system laid the foundation for all subsequent technologies.

📖 Chapter III – The Rise of Crossbar Systems (1930–1960)

3.1. Why a new technology was needed

By the early 1930s, step-by-step Strowger switchboards dominated telephone networks. However, they had clear limits:

high noise and mechanical wear;
relatively long connection times;
high consumption of space and energy;
difficulties in expanding to hundreds of thousands of subscribers.

A new generation of power plants was needed to cope with accelerated urbanization and higher reliability requirements.

3.2. Principiul crossbar

The crossbar system was invented and perfected in the 1920s–30s (first implemented at AT&T and Ericsson).

Architecture:

o bare metalice matrix (orizontal + vertical);
at the intersections there were electromechanical contacts;
When a call was initiated, the bars intersected and established the connection.

Advantages:

Faster connection speed.
Fewer moving parts = increased reliability.
Higher capacity (tens of thousands of subscribers in the same exchange).
Possibility of introducing multi-frequency signalling and additional services.

3.3. Development in the US and Europe

USA: Western Electric and Bell Labs develop the first commercial crossbar boilers (1938, New York).
Sweden: Ericsson launches its own crossbar system, adopted in Scandinavia and then exported worldwide.
Germany and France: gradually adopt technology after 1945, in post-war reconstruction.

3.4. Impact of the Second World War

The war slowed the expansion of civilian telephony, but stimulated technical development. Armies needed robust, fast, and reliable communications. Crossbar proved to be a promising technology, and after 1945 it became standard in many countries.

3.5. Interwar Romania and the first modern power plants

SART and modernization

In Romania, the interwar period brought a real revolution in telecommunications through the Romanian Anonymous Telephone Company (SART), a concession associated with ITT.

1931–1933: construction of the Palace of Telephones on Calea Victoriei, Bucharest.
Establishment of a modern urban network, including automatic control panels.
The first implementations of advanced technology, setting the stage for the crossbar era.

3.6. Post-war Romania (1945–1960)

After the war, Romania came under the influence of the Eastern bloc. Telephone systems have been rebuilt and standardised.

Pentaconta crossbar boilers (of French origin, adapted in various socialist countries) are installed.
The local production of equipment is developed at Electromagnetica / Standard Electrică Romanian.
The capacity of urban power plants is increasing significantly, reaching tens of thousands of subscribers in Bucharest and major cities.

3.7. Technical characteristics of crossbar

Fast switching: connections made in fractions of a second.
Reliability: parts less susceptible to wear than the Strowger.
Flexibility: enable advanced signaling and connection to long-distance networks.
Scalability: high-capacity power plants, suitable for expanding cities.

3.8. Social and economic impact

Increased access: more citizens and companies could have a telephone.
Long distance call automation: direct contact between cities, without an operator.
Modernization of the national image: a modern telephone system was a symbol of progress.

In Romania in the 1950s, the telephone remained a relatively rare commodity, but crossbar exchanges allowed the service to gradually expand to the urban middle class.

3.9. Conclusions for the crossbar era

Between 1930 and 1960, crossbar systems represented the second great revolution in telephony:

they gradually replaced Strowger's step-by-step;
enabled the massive expansion of urban and interurban networks;
have created the necessary infrastructure for the subsequent transition to programmed control (SPC) and then to digitalisation.

For Romania, this was the era of consolidation of modern telephony, in which the Palace of Telephones and the crossbar switchboards became symbols of technical progress.

📖 Chapter IV – Post-war reconstruction and standardization (1945–1960)

4.1. Historical context after 1945

World War II left behind a devastated continent, including in terms of telecommunications infrastructure. Telephone lines cut, switchboards bombed, telecommunications buildings destroyed – all of this required rebuilding from scratch in many states.

The West: benefited from the Marshall Plan, which accelerated the restoration and modernization of networks.
Eastern Bloc: rebuilt more slowly, under difficult economic conditions, but with a focus on standardization and local production.

Telephony became an essential element for the administration of the state, the coordination of the economy and urban life.

4.2. Network reconstruction in Western Europe

France: launched an extensive program to restore the telephone network, switching to crossbar exchanges and preparing the ground for the Pentaconta.
Germany: rebuilt the infrastructure quickly, deploying modern power plants, especially in West Germany.
UK: Continued crossbar expansion and planned to introduce electronic systems.

The West has managed to turn the reconstruction into an opportunity for technical modernization.

4.3. Reconstruction in the Eastern Bloc

In Eastern Europe, including Romania, reconstruction was guided by the Soviet model:

existing Western technology (Strowger and crossbar) was taken over, but local solutions were adapted;
focus on domestic production to reduce dependence on imports;
the development of national telecommunications companies as pillars of the socialist economy.

In the Soviet Union, automatic power plants were adapted and produced locally, with Western influences but also their own innovations.

4.4. The situation in Romania after the war

Romania has suffered large losses in telecommunications infrastructure.

Many long-distance lines were destroyed or damaged.
Urban power plants, including in Bucharest, needed major repairs.
The Palace of Telephones survived the war and remained the symbolic center of communications.

In the 1950s, the Romanian state took full control of the telephone networks and began expansion and standardization programs.

4.5. Standardisation of equipment

In order to ensure efficiency, the authorities in Romania (and other Eastern countries) have decided:

adoption of a unitary system of power plants (Pentaconta crossbar);
manufacturing of equipment at local level (Electromagnetics / Romanian Electrical Standard);
the use of a standardised progressive numbering system;
implementation of automated long-distance networks.

This standardization has reduced costs and made it easier to train technicians.

4.6. The first long-distance automation

A big step forward after 1945 was the introduction of automated, operatorless long-distance calls.

In the West: the first automatic long-distance networks appear in the late 1940s.
In Romania: the process begins timidly in the 1950s, with the expansion of the links between Bucharest and the big cities.

Although the infrastructure was limited, it paved the way for a modern national network.

4.7. Formation of State networks

In Romania, telephony becomes part of a centralized system:

The Ministry of Posts and Telecommunications coordinated the entire network.
Telephony was considered a strategic service, vital for the administration and the army.
However, the population's access to the telephone remained limited, due to costs and the prioritization of institutions.

4.8. Social and economic impact

Even though the number of subscribers was relatively small, telephony played a key role:

Economic coordination: factories, ministries and the army needed fast communications.
Urban life: in Bucharest and other large cities, the telephone had become an indispensable tool for administration and commerce.
The image of modernity: although access was limited, the presence of modern switchboards and the Palace of Telephones was a proof of technical progress.

4.9. Limits of development in the 1950s

The capacity of the power plants remained insufficient for the population's demand.
The waiting time for the installation of a phone could exceed several years.
Crossbar technology, although modern, was expensive and required a lot of space.

These limits will determine the transition, in the coming decades, to electronic and then digital systems.

4.10. Conclusions for the period 1945–1960

The post-war period meant:

Reconstruction after the destruction of the war.
Standardization of equipment for efficiency.
Strengthening national state networks.
Preparing the ground for the SPC and digital era.

For Romania, the years 1945–1960 were the years of restoration and standardization, in which the foundations of socialist telephony were laid.

📖 Chapter V – The Industrialized Crossbar Era and the Transition to SPC (1960–1980)

5.1. Global context in the 1960s

By the early 1960s, telephony had already become a mainstream service in many industrialized countries. However, classic crossbar technology was starting to show limits:

exponential growth in the number of subscribers, especially in large cities;
the need for fast and reliable long-distance calls;
the emergence of international communications and satellites;
Requirement for additional services (call waiting, conferences, special numbers).

Thus, large telecommunications companies have been looking for more advanced automation solutions.

5.2. The Pentaconta family and crossbar industrialization

One of the most important crossbar systems developed after 1960 was the Pentaconta family (in France, then adapted in several countries).

Features:

increased reliability;
large capacities (up to hundreds of thousands of subscribers);
modularity (the possibility of expanding the network by adding modules).

These systems have been used in many countries in Europe and Latin America, marking the pinnacle of electromechanical technology.

5.3. Long-distance automation

The 1960s–70s brought a crucial innovation: the automation of long-distance calls.

Until then, many long calls required human operators.
With the new crossbar control panels and the introduction of multi-frequency signalling, long-distance calls could be made directly by subscribers.
This has reduced login time and increased user trust.

5.4. Received systems SPC (Stored Program Control)

A key step towards the digital age was the introduction of programmed control panels (SPCs).

Concept: separation of the switching plane (crossbar or electronic) from the control plane, now achieved by programmable microprocessors.
Advantage: enormous flexibility – new functions could be added through the software without major hardware changes.
First implementations: 1965–70 in the USA, Japan and Western Europe.

SPC was the "bridge" between electromechanical technology and the future fully digital power plants.

5.5. Situation in Romania (1960–1980)

Extinderea crossbar

In Romania, in the 1960s–70s, Pentaconta crossbar boilers were widely implemented:

Bucharest and the big cities (Cluj, Iasi, Timisoara, Constanta) received modern urban power plants.
The capacity of the plants has increased from a few thousand to tens of thousands of subscribers.
Automated long-distance calls have gradually become possible.

Local production

At Electromagnetica and other telecommunications factories, Romania produced crossbar equipment and landline telephones, on adapted licenses.

Limitations

The telephone remained a rare commodity for the average population.
The demand far exceeded the supply: the waiting list for a telephone line could be 5–10 years.
Priority was given to state institutions, factories and political elites.

5.6. Global developments in parallel

USA: Bell Labs introduced the first large-scale SPC systems (No.1 ESS, 1965).
Europe: Ericsson and Siemens switched to programmed control electronic switchboards.
Japan: Companies such as NEC and Fujitsu were developing high-capacity electronic power plants.

Thus, while Romania and many Eastern countries remained at the classic crossbar, the West was already taking the step towards the electronic age.

5.7. Social and economic impact

Even with its limitations, crossbar expansion has had major effects:

increasing urban telephone density;
developing trade and administration through faster communications;
Image of technical progress – large power plants were symbols of modernity.

In Romania, the telephone remained a status symbol – restricted access accentuated the prestige of the owners.

5.8. Preparing for the digital age

The 1970s–80s were the years of transition:

crossbar was still dominant, but SPC was increasingly imposing;
the first concepts of digitization of the voice (PCM – Pulse Code Modulation) were already tested;
the big companies (Alcatel, Ericsson, Siemens, AT&T) were preparing the systems that would dominate the 1980s and 1990s.

5.9. Conclusions for the period 1960–1980

This era marks:

the peak of the crossbar (industrialized high-capacity systems);
the birth of the SPC, the beginning of the electronic and programmable era;
for Romania, a period of partial modernization, but also of access restrictions.

It was the next step – massive digitization – it was already ready.

📖 Chapter VI – Digitalisation (1980–2000)

6.1. Why digitization was needed

By the early 1980s, analog telephony (crossbar + SPC) had reached its limits. The problems were:

Call quality: noise, attenuation, long-distance limitations.
Insufficient capacity: exponential increase in demand for telephone lines.
Limited services: Inability to integrate data and voice on the same channel.
Expensive maintenance: large electromechanical equipment with parts subject to wear.

The solution: switching from analog to digital.

6.2. Technical principles of digitalisation

PCM – Pulse Code Modulation

Conversion of voice signal into digital pulses (0 and 1).
Rată standard: 64 kbps per canal.

TDM – Time Division Multiplexing

Dividing a digital channel into time slots.
The ability to carry dozens or hundreds of calls on the same line.

ISDN – Integrated Services Digital Network

Published at the end of the '80s.
It allowed the integration of voice, data and fax on the same line.

6.3. Large Digital Systems (1980–2000)

Alcatel 1000 E10 (France)

Modular system, widespread in Europe and Africa.
Support voice, ISDN and SS7 signaling.

Ericsson AXE (Suedia)

Launched in 1976, expanded in the 80s–90s.
Control APZ (computer) + module de commutare digitale.
Exported to more than 100 countries.

Siemens EWSD (Germany)

Extremely robust system, dominant in Germany and Central Europe.

AT&T 5ESS (SUA)

Massively implemented in North America.
Versatile, it supported both landline telephony and smart grid services.

6.4. Romania and digitalisation

The situation of the '80s

Romania remained mostly on the crossbar, with few SPC electronic control panels.
Telephony was a luxury service: waiting lists of 5–10 years for a line.
Priority: state institutions, the army, the political elites.

The '90s – the digital leap

After 1989, Romania experienced an accelerated modernization:

Romtelecom (successor of the state network) has invested heavily in digitalization.
Alcatel E10 and Ericsson AXE boilers were installed, gradually replacing the crossbar.
The first ISDN services for companies also appeared.

Mobile telephony

1993–94: The first analog mobile networks (NMTs).
1996: GSM licenses (Connex, Dialog).
The emergence of mobile telephony has also increased the pressure to modernize fixed networks.

6.5. New services brought by digitalisation

Call on hold.
Conference in three.
Special numbers (0800, 0900).
Smart networks (IN): prepaid cards, centrex.
Low-speed data (ISDN) – precursor to dial-up internet.

6.6. Economic and social impact

In the world

Fixed telephony is becoming a universal service in developed countries.
The volume of international calls is massively increasing.
Digital networks are creating the basis for the global internet.

In Romania

Access to the telephone is gradually democratized in the 90s.
In Bucharest, telephone density is increasing rapidly, but rural gaps persist.
The advent of GSM completely changes the perception of telephony.

6.7. SS7 signalling and the communications revolution

A key element of digitalization was the introduction of Signage No. 7 (SS7):

separate channels for call control;
high connection speeds;
smart services and GSM roaming.

Without SS7, modern mobile telephony would not have been possible.

6.8. Limits of the period 1980–2000

High costs: digitization requires huge investments.
Uneven infrastructure: developing countries have lagged behind.
The decline of the landline: even in the midst of digitalization, mobile telephony was starting to gain ground.

6.9. Conclusions for the period 1980–2000

Digitalization was the third great revolution in the history of telephone exchanges:

the voice has become a digital signal;
services have been expanded and diversified;
digital networks have prepared the emergence of the Internet and IP communications.

For Romania, the '90s were the period of a leap from obsolete infrastructure to a modern network, compatible with the West.

📖 Chapter VII – The IP Era and Softswitch (2000–2020)

7.1. Why a new change was needed

At the end of the 90s, digital TDM exchanges (E10, AXE, EWSD, 5ESS) dominated fixed telephony. However, the advent of the commercial internet and data services has put huge pressure on traditional infrastructure:

TDM networks were efficient for voice but inefficient for data;
the operating costs were high;
Users demanded the integration of services (voice, fax, data, video) into a single platform.

Thus, the 2000s brought the transition to IP-based networks and the emergence of the softswitch.

7.2. Softswitch Concept

A softswitch is a virtualized telephone exchange, implemented in software.

Control plane: manages calls via IP protocols (SIP, H.323).
Transport plan: Voice traffic is converted into IP packets and sent over data networks.
Media gateways: Connect IP networks with traditional TDM networks.

Advantages:

Low cost – software on standard servers, not specialized hardware.
Flexibility – easy to update via software.
Integration – voice + data + video on the same infrastructure.
Scalability – increasing capacity by adding servers.

7.3. Emergence of VoIP

Voice over IP (VoIP) started as an experimental technology in the 90s and became mainstream in the 2000s.

Skype (2003): popularized free calls on the Internet.
Traditional operators: have gradually introduced VoIP services to reduce costs.
IT companies: Cisco, Huawei, and others have become major suppliers of equipment.

7.4. IMS (IP Multimedia Subsystem) standardization

To organize the chaos of VoIP technologies, the industry has created the IMS (IP Multimedia Subsystem), a standardized architectural framework:

uses SIP (Session Initiation Protocol) to control calls;
integrates voice, video, messaging, data;
allows advanced services: VoLTE (Voice over LTE), converged fixed-mobile services.

IMS has become the foundation of 4G and 5G networks.

7.5. Situation in Romania (2000–2020)

Fixed telephony

2000–2010: Romtelecom (the former national operator) gradually migrated from TDM switches to softswitches.
2010–2020: Many E10 and AXE plants were decommissioned, replaced with IP platforms.
Massive decrease in the number of fixed subscribers as mobile became dominant.

Mobile telephony

2000–2010: GSM explozia (Orange, Vodafone, Cosmote).
2014: Introduction of 4G and VoLTE services.
2020: the first commercial 5G networks.

Alternative Operators

RCS-RDS (Digi) introduced VoIP services and developed a national all-IP network.
Small companies have used open-source softswitches (Asterisk, FreeSWITCH) for niche services.

7.6. Economic and social impact

Reduced costs for users: much cheaper international calls via VoIP.
Fixed-mobile convergence: integrated subscriptions with voice, internet and television packages.
Universal access to communications: almost the entire population had a mobile phone until 2010.
The transformation of the internet: voice has become just a service among other things, not the "center" of the network.

7.7. Problems and challenges

The quality of VoIP calls at first was poor (latency, echo).
Security: interceptions, frauds (VoIP fraud, SIM-box).
Compatibility: The transition from TDM to IP required complex gateways.
Decline of the fixed rate: incumbents have lost a large part of their revenues.

7.8. Conclusions for the period 2000–2020

This era marks the fourth great revolution of telephone exchanges:

voice becomes an IP application, not a dedicated service;
softswitch and IMS replace TDM switchboards;
the mobile becomes dominant, the fixed enters into decline;
Romania is making the transition to IP networks in parallel with the rest of Europe, benefiting from liberalization and competition.

📖 Chapter VIII – Virtualization and Cloud Networking (2020–present)

8.1. De la softswitch la cloud-native

After 2020, the telecommunications industry entered a new stage: the complete virtualization of network functions.

If in the 2000s the control panels were already software (softswitch), now they have become cloud-native.
Control and switching functions no longer run on dedicated servers, but on virtual machines or cloud containers .
Operators use technologies such as NFV (Network Functions Virtualization) and SDN (Software Defined Networking) to manage traffic.

8.2. IMS and the 4G/5G era

IMS (IP Multimedia Subsystem) remained the standardized framework, but the implementation moved to the cloud.

VoLTE (Voice over LTE): voice carried over 4G over IP, replacing circuit-switched fallback.
VoWiFi: Calls over Wi-Fi networks, integrated with IMS.
VoNR (Voice over New Radio): native 5G voice, launched after 2020.

Thus, the traditional phone call has become an IP application among other things.

8.3. Virtualization technologies

NFV (Network Functions Virtualization)

Network functions (softswitch, gateway, firewall) run as VMs or containers.
Benefit: lower costs, increased flexibility.

SDN (Software Defined Networking)

Separates the control plane from the transport plane.
Allows dynamic configuration of traffic flows.

Cloud-native 5G Core

All functions (AMF, SMF, UPF) run as microservices.
Integration with Kubernetes, OpenStack platforms.

8.4. Romania in the post-2020 era

Fixed telephony

The number of fixed subscribers continued to decline.
Romtelecom (now Telekom, later Orange Romania Communications) closed many TDM plants.
RCS-RDS (Digi) implemented an all-IP network, without TDM.

Mobile telephony

2020: the first commercial 5G networks launched in Bucharest and several large cities.
2021–2023: 5G expansion, with support for VoNR.
Large operators (Orange, Vodafone, Digi) use virtualized and cloud-native architectures.

8.5. Economic and social impact

Low costs: Operators run network functions on standard servers, not expensive hardware.
Scalability: Network capacity can be increased by adding cloud resources.
New services: HD video, VR/AR, IoT, connected vehicles.
The decline of classic telephony: traditional calls are now only a small part of total traffic.

8.6. Challenges

High complexity: Virtual network management requires advanced IT skills.
Security: IP networks are more exposed to cyberattacks.
Massive investments: the transition to 5G and the cloud required billions of euros.
Dependence on global suppliers: Huawei, Ericsson, Nokia, Cisco dominate the market.

8.7. Future outlook (2025–2035)

6G: research targets terabite speeds and latencies below 1 ms.
Autonomous networks: AI and machine learning for automatic traffic optimization.
Massive IoT integration: billions of connected devices (cars, sensors, robots).
Holographic services and mixed reality: Video and audio calls will be replaced by immersive experiences.

8.8. Conclusions for the period 2020-present

The era of virtualization and the cloud represents the fifth great revolution of telephone exchanges:

plants are no longer physical "boxes", but applications in the cloud;
voice is just one service among many others, carried by the IP network;
Romania is participating in this transition in parallel with the rest of Europe, by expanding 5G and decommissioning TDM;
the future belongs to 6G, AI, and holographic communications.

📖 Chapter IX – Interwar Romania (1919–1939)

9.1. Context general

After World War I, Greater Romania needed a modern communications infrastructure to administer the new provinces and support the rebuilding economy. Telephony, until then limited to a few thousand subscribers, had to be extended.

9.2. Establishment of SART (1930)

The Romanian Anonymous Telephone Company (SART) was created in 1930, as part of an agreement between the Romanian state and the American company ITT (International Telephone and Telegraph).
The 49-year concession granted SART the right to manage the national telephone network and the obligation to modernize it.
ITT brought capital, modern equipment and know-how.

This was a decisive moment: Romania has entered the era of modern telephony.

9.3. The Palace of Telephones (1931–1933)

Built on Calea Victoriei, Bucharest.
Art deco architecture, a symbol of technical progress.
It housed modern automatic control panels, offices and spaces for operators.
It has become an urban symbol and an architectural landmark.

9.4. Expansion of automatic control panels

In the '30s, Romania installed automatic Strowger and crossbar control panels in several cities: Bucharest, Cluj, Timisoara, Iasi, Constanta.

Urban numbering has increased to 5 digits in Bucharest.
The capacity of the plants has increased to tens of thousands of subscribers.
Subscribers could dial the numbers themselves, without an operator.

9.5. Social impact

The telephone becomes a symbol of urban modernity.
The subscribers were generally institutions, companies, doctors, lawyers, social elites.
The cost remained high, but the network was expanding rapidly.

9.6. International comparison

Romania was relatively synchronized with Western Europe.
While London or Paris had hundreds of thousands of subscribers, Bucharest had several tens of thousands – but the technology was the same.
The Palace of Telephones was comparable in infrastructure to Western centers.

9.7. Conclusion

The interwar period was the era of accelerated modernization of the Romanian telephony:

the emergence of SART and the Palace of Telephones;
the introduction of automatic control panels in large cities;
The phone as a symbol of progress and prosperity.

📖 Chapter X – Post-war reconstruction in Romania (1945–1960)

10.1. General context after the war

The Second World War seriously affected Romania's telecommunications infrastructure:

many intercity lines were destroyed or damaged;
urban power plants damaged by bombing and lack of maintenance;
Worn and obsolete equipment, difficult to replace due to economic restrictions.

After 1945, the new communist political regime considered telecommunications a strategic priority, but resources were extremely limited.

10.2. Nationalisation of telephony

In 1948, with the nationalization of the economy, the telecommunications network passed entirely under the control of the Ministry of Posts and Telecommunications.
SART, the interwar concessionary company associated with ITT, was disbanded.
The Palace of Telephones and the entire urban infrastructure have become the property of the state.

This marked a rupture: Romanian telephony was moving from the Western capitalist model to a centralized, state-owned one.

10.3. Restoration of urban infrastructure

The years 1945–1955 were dedicated to the restoration of the urban power plants:

many interwar automatic power plants were repaired and put back into operation;
in Bucharest, the Palace of Telephones remained the main center of the network;
Additional power plants have been installed for the developing neighborhoods.

The capacity of the urban network grew slowly, but the priorities were mostly administrative and military.

10.4. Long-distance reconstruction

A big problem of the period was the restoration of long-distance connections:

long-distance overhead lines were vulnerable and often damaged;
they have been gradually replaced by underground cables between major cities;
the Bucharest–Cluj, Bucharest–Iasi and Bucharest–Timisoara connections have become priorities.

10.5. Standardisation of equipment

In the 1950s, Romania began to standardize the network:

the old manual boilers were gradually replaced by crossbar systems;
the Pentaconta family (of French origin, but also adapted to the socialist bloc) was chosen;
the local production of equipment was encouraged, through factories such as Electromagnetica and Standard Electrică Romanian.

10.6. Access of the population

The telephone remained a rare commodity in the period 1945–1960:

most of the subscribers were state institutions, factories, ministries;
the civilian population had very limited access;
in Bucharest, the phones were concentrated in central and institutional neighborhoods.

Thus, telephony was an instrument of the state, rather than a universal service.

10.7. The Palace of Telephones – a symbol of continuity

Although built in the interwar capitalist period, the Palace of Telephones remained a landmark even in the socialist era:

it housed the main power plants for Bucharest;
it was perceived as the "heart of the national telephone network";
symbolized, paradoxically, both interwar modernity and the new post-war order.

10.8. International comparison

The West: telephone networks were rapidly rebuilt with the help of the Marshall Plan, and telephone density increased rapidly.
Romania and the Eastern bloc: reconstruction was slower, with restricted access and partially obsolete technology.
However, Romania managed to maintain a decent technical level, thanks to crossbar standardization.

10.9. Social and economic impact

Telephony allowed the coordination of the centralized economy.
State institutions and the military now had reliable networks for internal communications.
For the population, the reduced access has kept the phone as a symbol of prestige.

10.10. Conclusion for the period 1945–1960

The post-war years in Romania meant:

nationalization and total centralization of telephony;
the restoration of urban and interurban infrastructure;
standardization of crossbar equipment;
maintaining the telephone as a state instrument, not as a universal service.

The period laid the groundwork for the massive expansion of the 1960s–80s, but the gap with the West began to widen.

📖 Chapter XI – The Crossbar Era and Industrialization in Romania (1960–1980)

11.1. Context general

The 1960s and 1980s marked a stage of accelerated industrialization and expansion of telephone networks in Romania, in parallel with the massive urbanization of the population. The communist regime considered telephony a strategic tool for the economy, administration and army.

In this context, Pentaconta crossbar switchboards have become the backbone of the national telephone network.

11.2. Introduction of the Pentaconta system

Origin: The Pentaconta system was developed in France, but the license and technical principles were also adopted in other countries.
Features: high-capacity electromechanical control panel, based on crossbar matrix, reliable and scalable.
Implementation in Romania: since the 1960s, Pentaconta plants have been installed in Bucharest and in major cities.

This choice standardized the entire network and allowed for local industrial development.

11.3. Local production of equipment

In order to reduce dependence on imports, Romania has developed the local production of equipment:

Electromagnetica and Standard Electrică Romanian produced components for switchboards and telephone sets.
Crossbar parts, racks, cables and office phones were manufactured.
Many of the landline telephone sets (black or cream) used in Romania in the '70s were produced locally.

11.4. Extension of the urban network

In Bucharest, the network has grown to tens of thousands of subscribers.
New neighborhoods (Drumul Taberei, Titan, Berceni) have received their own power plants.
In large cities, new urban power plants have appeared, integrated with the interurban network.

However, the number of lines was still insufficient for the actual demand.

11.5. Long-distance automation

A major breakthrough of the period was the introduction of automated long-distance calling:

Subscribers could dial the number of another city on their own, without an operator.
This reduced login time and increased user satisfaction.
Bucharest has become the "hub" of the long-distance network.

11.6. Limitations and Issues

Limited access: Setting up a phone at home was difficult. Many citizens waited for years on the priority lists.
Priority for the state: ministries, enterprises, the army and the security had privileged access.
Variable quality: Long distance calls were often noisy and interrupted.
High costs: crossbar boilers required a lot of space and constant maintenance.

11.7. The phone as a social symbol

In Romania in the '70s:

a landline phone installed at home was a sign of social prestige;
many families used their neighbors' phones for emergencies;
Public telephone booths were rare and often crowded.

The telephone remained a controlled "commodity", distributed on social and political criteria.

11.8. Compared to the West

West: In the 1970s, telephone density in Western Europe was high (50–70% of households).
Romania: the density was much lower (below 10% at national level).
However, the technology used (Pentaconta crossbar) was comparable in principle to that of the West.

The gap was mainly in terms of access, not technology.

11.9. Economic and strategic impact

The telephone network allowed for the centralized coordination of the socialist economy.
Factories, cooperatives and ministries relied on the phone for daily reporting.
The army and security had dedicated networks, partially integrated with the civilian ones.

11.10. Preparing for the SPC and digital era

The 1970s–80s were a period of peak for crossbars, but also of transition to programmed control (SPC).

Romania has started importing and testing SPC electronic control panels.
However, limited resources meant that the crossbar remained dominant until the 90s.

11.11. Conclusions for the period 1960–1980

This period represented:

industrialization of telecommunications through local production of equipment;
expansion of Pentaconta crossbar power plants in major cities;
long-distance automation;
maintaining the phone as a rare and privileged commodity;
(delayed) preparation for the digital age.

📖 Chapter XII – Digitalization in Romania (1980–2000)

12.1. Romania's global context and gap

At the beginning of the 80s, many Western countries were already switching to digital powerhouses:

Alcatel 1000 E10 in France,
Ericsson AXE in Sweden,
Siemens EWSD in Germany,
AT&T 5ESS in the US.

Romania, under the communist regime, has lagged behind:

the network was still based on Pentaconta crossbar boilers,
access to the population was severely limited,
The demand was huge, but the financial and technical resources were scarce.

12.2. The situation of the '80s

The landline phone was considered a luxury.
Waiting lists for a telephone line could reach 10–15 years.
Priority was given to state institutions, the army, the security and political elites.
Household subscribers were few and often chosen on the basis of "file" criteria.

Digital technology was known to specialists, but there was no internal industrial capacity for implementation.

12.3. Change after 1989

The fall of the communist regime opened the way for modernization:

The national network came under the control of Romtelecom, established in 1991.
Romania has started an extensive digitalization program with the support of large Western companies.
The objective: the gradual replacement of crossbar boilers with digital boilers.

12.4. Digital power plants installed in Romania

Alcatel 1000 E10

France was the main technological partner.
The first E10 power plants were installed in Bucharest and major cities in the early 90s.
They supported voice, ISDN, SS7 signaling.

Ericsson AXE

Introduced in Romania in the mid-90s.
They used the modular architecture with APZ control and digital switching.
They became the backbone of the long-distance network.

Siemens EWSD

There were also German implementations, although fewer.

Thus, Romania has managed to bring the infrastructure to a level comparable to European standards.

12.5. New services in Romania in the '90s

Call on hold.
Conference in three.
Short numbers (information, emergencies).
0800 – the first toll-free numbers.
ISDN – for companies, a timid start.

Although these services were limited at first, they marked Romania's entry into the digital age.

12.6. The emergence of mobile telephony

The digitization of the landline coincided with the emergence of mobile telephony:

1993–94: The first analog NMT networks.
1996: GSM licenses for Connex and Dialog (today's Vodafone and Orange).
Mobile telephony has exploded, providing quick access to millions of users.

For many Romanians, the first phone was not landline, but mobile.

12.7. Economic and social impact

Rapid expansion of access: The number of phone subscribers has increased significantly.
Economic integration: Romanian companies could communicate more easily with foreign partners.
Cultural change: The phone ceased to be an extreme luxury and gradually became a more affordable good.
Migration to mobile: many citizens have chosen GSM directly, bypassing fixed telephony.

12.8. Problems and limits

Large disparities between urban and rural: large cities digitalised rapidly, but many villages were left without a telephone until after 2000.
High costs: subscriptions were expensive for the average population.
Incomplete transition: crossbar boilers continued to exist until the 2000s.

12.9. International comparison

The West: By the 1990s, many countries had already completely gone digital.
Romania: started with a gap, but quickly recovered it after 1995, mainly due to foreign investments.
Particularity: Romania has "skipped stages" through the GSM explosion, which compensated for the lack of universal fixed telephony.

12.10. Conclusions for the period 1980–2000

The last communist decade was one of stagnation and deprivation.
After 1989, Romania entered the digital era with the installation of Alcatel E10 and Ericsson AXE boilers.
The emergence of mobile telephony has radically changed the dynamics of the market.
The phone has gone from the luxury zone to the social and economic necessity zone.

📖 Chapter XIII – Romania and the IP transition (2000–2025)

13.1. Context of the 2000s

After the digitization of the '90s, Romania was in a paradoxical situation:

finally had modern power plants (E10, AXE, EWSD),
but fixed telephony was in decline due to the GSM explosion,
And the Internet was beginning to become the new "engine" of communications.

In this context, Romanian operators were forced to make the transition from TDM to IP.

13.2. Romtelecom and the modernization of the fixed network

2000–2010: Romtelecom began to gradually replace TDM switchboards with softswitches and media gateways.
2010–2020: Many E10 and AXE plants were decommissioned.
IP platforms, compatible with IMS, have been introduced.
In 2021, Romtelecom was absorbed into Orange Romania Communications, continuing the migration to full-IP networks.

13.3. RCS & RDS (Digi) – un model all-IP

From the beginning, Digi has relied on an all-IP infrastructure, with soft switches and modern equipment.
It has developed fiber optic networks and integrated services (voice, internet, TV).
It was the first operator to deliver large-scale VoIP services to the population.

13.4. Liberalisation and competition

After 2003, the telecom market in Romania was liberalized.
Small alternative operators have emerged, using VoIP platforms based on open-source softswitches (Asterisk, FreeSWITCH).
This led to lower tariffs and diversification of services.

13.5. Transition to IMS and mobile networks

With the advent of 4G, Romanian operators have implemented VoLTE (Voice over LTE) on IMS architectures.
In 2020–2023, the first commercial 5G networks introduced VoNR (Voice over New Radio).
Thus, traditional calls have become simple IP streams.

13.6. Declines and transformations of fixed telephony

The number of fixed telephony subscribers has been steadily decreasing since 2005.
Many Romanians have completely given up the fixed line, preferring the mobile.
In some rural areas, landline has almost completely disappeared.

However, the fixed network has turned into support for the internet and VoIP, not for classic voice.

13.7. New services in the IP era

Residential VoIP (integrated internet + voice subscriptions).
Fixed-mobile convergence: triple play packages (TV + internet + telephony).
Free network calls and extremely low international rates.
VoWiFi: Wi-Fi calls, integrated into the mobile offer.

13.8. Romania and broadband internet

A key element of the IP transition has been the development of fiber optic networks:

Romania has become one of the countries with the highest average internet speed in Europe.
Fiber networks have supported the complete migration to VoIP and IMS.
Many Romanians have directly experienced the transition to IP without realizing it: the landline phone was now connected to an ONT (Optical Network Terminal), not to a TDM switchboard.

13.9. Social and economic impact

Universal access: until 2015, almost the entire population had a mobile phone.
Cheap services: Romania has become one of the cheapest telecom markets in the EU.
Transformation of the fixed: for the majority of the population, the fixture has disappeared from everyday life.
Convergence: telephony has become just a bundled service with internet and TV.

13.10. Challenges and limits

Depopulation of villages: many rural areas have never benefited from the classic fix; they have switched directly to mobile.
Dependence on foreign equipment: Romania has used Alcatel, Ericsson, Huawei, ZTE technologies.
Cybersecurity: IP networks are vulnerable to attacks, requiring strict regulations.

13.11. 2020–2025: VoNR and cloud-native

Romanian operators are implementing 5G SA (standalone), with cloud-native network functions.
Calls are managed via IMS in the cloud, and TDM switchboards have been almost completely taken out of service.
Romania is now at a level comparable to other European countries in terms of infrastructure.

13.12. Conclusions for the period 2000–2025

The IP transition meant for Romania:

the closure of the era of the traditional power plant,
turning the landline phone into a residual VoIP service,
the explosion of mobile telephony and the internet,
integration into European and global standards,
readiness for the 6G era and AI in telecommunications.

Telephony, once a symbol of luxury and prestige, has today become a banal, invisible, but essential service, integrated into a much broader digital ecosystem.

📖 Extensive glossary of telephone exchanges and telecommunications

Subscriber – a natural or legal person who has a telephone line and a service contract with the operator. In the era of manual boilers, the subscriber was identified by the operator by name; with automation, through a unique number.

Asterisk – a very popular open-source softswitch since the 2000s, used for VoIP services, call centers and alternative operators.

Automatic Call Distribution (ACD) – functionality introduced in digital exchanges, used for call centers.

Bell Telephone Company – the company founded by Alexander Graham Bell, the forerunner of AT&T. The world's first major telephone company.

Broadband – term used for high-capacity data networks (high-speed internet). It enabled the integration of VoIP telephony and multimedia services.

Telephone exchange – equipment that allows the connection of calls between subscribers. It has evolved from manual panels (1878) to virtualized cloud systems (after 2020).

Centrex – smart grid service that offered private central exchange (PBX) functions through the public operator. Popular in Romania in the '90s–2000s.

Circuit-switched – the classic method of establishing a dedicated channel between two subscribers for the duration of the call. It has been replaced by packet switching (IP).

Crossbar – electromechanical power plant based on metal bar matrix (1930–1980). Faster and more reliable than Strowger.

Dial (telephone dial) – mechanism for forming telephone numbers by electrical impulses. It was standard in the twentieth century until the advent of keyboard phones.

Digital Switching – the process of routing calls as a digital signal, not an analog signal. The introduction of PCM/TDM has made this transition possible.

Digi (RCS & RDS) – Romanian operator that relied on all-IP infrastructure, becoming a leader in internet and VoIP in 2010–2020.

E10 (Alcatel 1000 E10) – French digital system, introduced in Romania in the 90s. Very widespread, he supported the modernization of Romtelecom.

Electromagnetica – Romanian telecommunications equipment factory, responsible for the production of crossbar control panels and fixed telephones in the '60s and '80s.

Ericsson AXE – Swedish digital system, one of the most performant, introduced in Romania in the '90s.

FreeSWITCH – open-source softswitch used in modern VoIP telephony, an alternative to Asterisk.

Fiber optics – transmission medium based on light pulses. It allowed the complete migration to IP and broadband internet in Romania.

Media gateway – equipment that connects classic TDM networks with IP networks. Used massively in the transition of the 2000s.

GSM (Global System for Mobile Communications) – digital standard for mobile telephony. Launched in Romania in 1996 (Connex and Dialog).

H.323 – VoIP protocol used in the 2000s, later replaced by SIP.

IMS (IP Multimedia Subsystem) – standardized architecture for multimedia services over IP. The foundation of VoLTE and VoNR networks.

ISDN (Integrated Services Digital Network) – standard from the 80s and 90s for integrating voice, fax and data on the same digital line.

Time multiplexing (TDM) – a digital technique by which several voice channels are transmitted on the same line, each with a time slot.

Mobile Switching Center (MSC) – the equivalent of a telephone exchange for mobile networks.

Telephone numbering – the system for assigning unique numbers to subscribers. In Romania, it evolved from 4–5 local digits to the current format +40 xx xxx xxxx.

NFV (Network Functions Virtualization) – a concept whereby network functions run virtually, not on dedicated equipment.

Telephone Palace (Bucharest) – emblematic building, built 1931–1933, symbol of modernity and headquarters for the SART network and then Romtelecom.

PBX (Private Branch Exchange) – private telephone exchange, used by companies.

Pentaconta – French crossbar boiler, standardized and produced in Romania in the '60s and '80s.

PCM (Pulse Code Modulation) – technique for digitizing the voice signal at 64 kbps.

SART (Romanian Anonymous Telephone Company) – a company created in 1930, in association with ITT, responsible for the interwar modernization of the Romanian telephony.

Softswitch – a telephone exchange implemented in software, used since the 2000s for VoIP.

SPC (Stored Program Control) – a concept introduced in the '60s and '70s, separates call control through software from switching equipment.

SS7 (Signalling System No.7) – digital signalling protocol that revolutionized telephony in the 80s and 90s.

Strowger (Step-by-Step) – the first automatic control unit (1892), based on step-by-step switching.

TDM (Time Division Multiplexing) – see Time Multiplexing.

Telekom Romania – the name of Romtelecom after 2014, later integrated into Orange Romania Communications.

VoIP telephony – voice transmitted over IP, replacing traditional circuit switching.

VoIP (Voice over IP) – technology by which voice is transmitted as IP packets.

VoLTE (Voice over LTE) – a service through which voice calls run natively on the 4G network.

VoNR (Voice over New Radio) – the equivalent for 5G, launched in Romania after 2020.

VPN (Virtual Private Network) – technology used to create virtual private networks over the internet.

Wi-Fi Calling (VoWiFi) – calls made over Wi-Fi networks, integrated into the offer of mobile operators.

📖 Detailed chronology of telephone exchanges (1876–2025)

1876–1890: The birth of the telephone and the first manual switchboards

1876 – Alexander Graham Bell patents the telephone.
1877 – the first experimental telephone lines in the USA.
1878 – The world's first telephone exchange, New Haven (Connecticut, USA), with 21 subscribers.
1879 – the first telephone exchange in London.
1880 – Paris installs the first manual boilers.
1881 – the first telephone lines in Bucharest.
1883–1884 – installation of the first small capacity manual power plants in Romania.
1890 – Romania has several hundred subscribers, most of them in Bucharest, Iasi and Galati.

1891–1930: Strowger Era and Automatic Switching

1891 – Almon B. Strowger files the patent for the first automatic power plant.
1892 – the first Strowger plant in La Porte, Indiana (USA).
1900 – Strowger becomes standard in the U.S.
1912 – London installs automatic control panels.
1920 – Japan adopts Strowger systems.
1920–1930 – the first discussions about automation in Romania.
1930 – the establishment of SART (Romanian Anonymous Telephone Company), associated with ITT.

1931–1960: Crossbar rise and post-war reconstruction

1931–1933 – construction of the Palace of Telephones in Bucharest, SART headquarters.
1930–1939 – installation of automatic power plants in Bucharest, Cluj, Timisoara, Iași.
1938 – New York installs the first large crossbar power plant.
1940–1945 – massive destruction of telephone infrastructure during World War II.
1948 – nationalization of telephony in Romania; SART is abolished.
1950–1955 – reconstruction of urban and interurban power plants.
1955 – Romania begins to standardize crossbar boilers (Pentaconta family).

1960–1980: Industrialized crossbar era and the beginnings of SPC

1960 – the peak of crossbar in Europe and the USA.
1965 – The US installs the first SPC system (No.1 ESS, Bell Labs).
1970 – Ericsson and Siemens launch programmed control panels.
1960–1970 – Romania installs Pentaconta crossbar boilers in major cities.
1970–1980 – local production of equipment at Electromagnetica and SER (Romanian Electric Standard).
1975 – the first fully automatic long-distance calls in Romania.

1980–2000: Massive digitalization

1980 – PCM and TDM become global standards.
1981 – Alcatel E10 implemented in France.
1983 – Ericsson AXE implemented on a global scale.
1985 – Siemens EWSD launched.
1980 – Romania remains at the crossbar, the landline remains a luxury.
1989 – change of political regime; the network falls under Romtelecom.
1991 – Romtelecom takes over the national network.
1993 – the first analog NMT mobile networks in Romania.
1995 – Romania installs the first Alcatel E10 digital control panels.
1996 – GSM licenses granted to Connex and Dialog.
1998 – the first Ericsson AXE plants in Romania.
2000 – ISDN and SS7 services become available in Romania.

2000–2020: IP transition and the mobile explosion

2000 – the first VoIP implementations globally.
2003 – launch of Skype.
2005 – introduction of IMS (IP Multimedia Subsystem).
2007 – Romania exceeds 10 million GSM subscribers.
2010 – Romtelecom starts decommissioning the E10 and AXE plants.
2010–2015 – RCS-RDS implements a national all-IP network.
2014 – VoLTE launched in Romania.
2015 – massive decrease in the number of fixed telephony subscribers.
2018 – Digi becomes the market leader in mobile telephony.

2020–2025: Virtualization and cloud-native

2020 – the first commercial 5G networks in Romania (Bucharest, Cluj, Iasi).
2021–2023 – 5G expansion in major cities.
2022 – the first VoNR (Voice over New Radio) calls in Romania.
2023–2025 – almost complete decommissioning of traditional TDM plants.
2025 – Romania has a full-IP, cloud-native telecom network, aligned with European standards.

📖 Full bibliography

I. International sources

Bell, A. G. – The Telephone: An Account of the Invention, Growth, and Use of the Telephone, Harper & Brothers, New York, 1878.
Casson, H. N. – The History of the Telephone, A.C. McClurg & Co., Chicago, 1910.
Brock, G. – The Second Information Revolution, Harvard University Press, Cambridge, 2003.
Lipartito, K. – The Bell System and Regional Business: The Telephone in the South, 1877–1920, Johns Hopkins University Press, Baltimore, 1989.
Mueller, M. – Universal Service: Competition, Interconnection, and Monopoly in the Making of the American Telephone System, MIT Press, Cambridge, 1997.
Pool, I. de Sola – Forecasting the Telephone: A Retrospective Technology Assessment of the Telephone, Ablex Publishing, Norwood, 1983.
Reid, L. – The Development of the Strowger Switch, IEEE Communications Magazine, 1985.
Schwartz, M. – Crossbar Switching in the Bell System, AT&T Technical Journal, 1960.
Stern, R. – Stored Program Control Switching Systems, IEEE Transactions on Communications, 1970.
Temin, P. – The Fall of the Bell System: A Study in Prices and Politics, Cambridge University Press, Cambridge, 1987.
Winston, B. – Media, Technology and Society: A History from the Telegraph to the Internet, Routledge, Londra, 1998.

II. Romanian sources

Constantinescu, N. – Telecommunications in Romania: History and Development, Romanian Academy Publishing House, Bucharest, 1985.
Dumitrescu, A. – Romanian Telephony in the Interwar Period, Technical Publishing House, Bucharest, 1975.
Ionescu, C. – The Palace of Telephones and the Modernization of Bucharest, Simetria Publishing House, Bucharest, 2010.
Popescu, M. – Distance Communication in Romania: From the Telegraph to the Internet, University Publishing House, Bucharest, 2008.
Stanciu, A. – Romtelecom and the transition to the market economy, Economic Publishing House, Bucharest, 2001.
Romtelecom Archives – internal documents on the digitization of the network in the '90s.
Telecommunications Magazine, various issues between 1960–2000, Bucharest.

III. Digital and online resources

ITU (International Telecommunication Union) – colecția de standarde: https://www.itu.int
ETSI (European Telecommunications Standards Institute) – arhiva de specificații: https://www.etsi.org
IEEE Xplore – academic articles on the history of telephone exchanges: https://ieeexplore.ieee.org
National Museum of American History (Smithsonian) – collection of phones and equipment: https://americanhistory.si.edu
"Dimitrie Leonida" Technical Museum, Bucharest – exhibitions and archive on Romanian telephony.
Telecom history blogs and forums (e.g. Telephone Collectors International).

IV. Journalistic and contemporary sources

Adevărul Newspaper, articles on the history of the Palace of Telephones, 2013–2020.
Ziarul Financiarul, articles on privatization and transition of Romtelecom, 2000–2014.
Biz Magazine, interviews with telecommunications managers, 2005–2020.

📖 Annex I – Evolution of telephone numbering in Romania

1. The first numbering systems (1881–1930)

In the early years, subscribers did not have actual numbers. The operator identified them by name or institution ("Connect me with Dr. Popescu").
As the number of subscribers increased, short numbers of 1–3 digits were introduced.
In interwar Bucharest (1920s), there were automatic Strowger control panels, and the numbering was 3 –4 digits, depending on the control panel.

2. Interwar numbering (1930–1945)

With the establishment of SART (1930), the numbering was standardized in Bucharest.
The Palace of Telephones and the automatic switchboards have allowed the expansion to 5 digits in Bucharest.
In other large cities (Cluj, Iași, Timișoara), the numbering varied between 3–5 digits, depending on the capacity of the plant.

3. Post-war era and crossbar (1945–1970)

In the 1950s and 1960s, Pentaconta crossbar boilers allowed the expansion to 6 digits in Bucharest.
However, the numbering was uneven at the national level: some small towns kept 3–4 digits.
Long distance calls required the city number + subscriber number to be dialed.

4. National standardization (1970–1990)

In the 70s, Romania began to standardize numbering.
Major cities have moved to 6–7 digits.
Bucharest: fixed numbering has reached 7 digits (prefix 1 + 6 digits for subscribers).
The intercity codes were 2 –3 digits: e.g. 01 Bucharest, 041 Constanta, 061 Iași.

5. Digital transition (1990–2000)

After 1990, with the installation of the E10 and AXE digital control panels, a new standardization was made.
The fixed numbering in Bucharest remained 7 digits, but the long-distance prefixes have been adjusted.
In the 90s, Romania adopted the international prefix +40.

6. Numbering reform (2002)

In 2002, Romania switched to the 10-digit national plan, according to European standards:

format: 0 + NDC + subscriber number;
e.g.: 021 for Bucharest, 0232 for Iași, 0256 for Timișoara.

The prefix "9" was reserved for special services (emergencies, police, firefighters).
The area code "8" for toll-free numbers (0800).
The prefix "90x" for special rate numbers.

7. VoIP and Mobile Era (2000–2025)

Fixed numbering has remained stable, but mobile telephony has introduced prefixes dedicated to operators:

072x – Connex/Vodafone,
074x – Dialog/Orange,
076x – Cosmote/Telekom,
077x – Digi Mobil.

VoIP services have also started to use classic geographic numbering, but targeted via IP.

8. State of play (2025)

Romania has a 10-digit national plan, completely standardized.
The +40 area code is used internationally.
Most internal calls are now made via IP, but the numbering has remained the same for compatibility.
There are discussions for the introduction of dedicated IoT (Internet of Things) prefixes and for 5G/6G services.

9. Comparative table of evolution

Period	Number of digits	Example Bucharest	Observations
1881–1920	1–3 digits	"2" = Doctor X	Call through operator
1930–1945	3–5 digits	12345	The first vending machines
1950–1970	6 digits	123456	Crossbar Pentaconta
1970–1990	7 digits	1xxxxxx	Prefix „1” București
1990–2002	7–8 digits	01-xxxxxx	Long Distance Hard Drives
2002–present	10 digits	021-xxxxxxx	Uniform plan

📖 Annex II – The main telephone exchanges in Romania (1900–2025)

1. Bucharest – the capital of Romanian telephony

Bucharest was the main center of the national network, with the most power plants and the largest capacities.

Table: Evolution of the power plants in Bucharest

Period	Location / Central	Type of technology	Observations
1883–1900	Manual central primele	Cord panels	Only a few hundred subscribers
1931–1933	The Palace of Telephones	Strowger automat	The first large urban automatic power plant
1950–1960	The Palace of Telephones + Extensions	Crossbar Pentaconta	Post-war standardization
1960–1980	Paper mills (Drumul Taberei, Titan, Berceni)	Crossbar Pentaconta	Integration of new neighborhoods
1990–2000	The Palace of Telephones + new switchboards	Digital E10, AXE	Rapid modernization, Romtelecom installations
2000–2010	Urban digital control unit	E10, AXE, EWSD	ISDN and SS7 service extension
2010–2020	Softswitch migrations	VoIP, IMS	Gradual shutdown of TDM control panels
2020–2025	Cloud IMS Orange/Digi	5G Virtualization	All-IP, VoLTE and VoNR network

2. Cluj-Napoca

The first manual boilers: the beginning of the twentieth century.
1930s: Strowger automatic control unit installed under SART.
1960–70s: Pentaconta power plants for the new districts (Mănăștur, Gheorgheni).
1990s: rapid digitization with Alcatel E10 boilers.
After 2000: migration to softswitch and IP networks.

3. Iasi

First telephone lines: 1880–1890, for administration and commerce.
Interwar period: SART automatic control unit.
Post-war: installation of crossbar boilers in Copou and Centre.
1990: Ericsson AXE digital control panel.
2020: VoIP and IMS, with integrated 5G network.

4. Timisoara

1881: one of the first cities in Romania with a telephone.
1930: Strowger automatic power plant.
1960–1980: expansion with Pentaconta in neighborhoods.
1990: E10 and AXE digital control panels.
2000+: migration to IP and fiber optics.

5. Constanta

Strong development after 1930, with the modernization of the port.
Automatic control panels installed in the interwar period.
Postbelic: crossbar Pentaconta.
1990–2000: Digital power station, then VoIP.
Strategic importance due to the port and military units.

6. Brașov

Interwar period: automatic control unit under SART.
1960–1980: Pentaconta power plants for new districts (Tractorul, Astra).
1990: Alcatel E10 digital control panel.
2000+: VoIP and IMS integration.

7. Other big cities

Galati, Craiova, Oradea, Sibiu – similar developments:

prime centrale manuale → automate Strowger (interbelic) → crossbar Pentaconta (postbelic) → digitale E10/AXE (anii ’90) → IP/IMS (după 2000).

8. Interurban and rural networks

In rural areas, until the 1960s–70s, small manual (hand-cranked) boilers predominated.
It was only in the 80s that there was a greater expansion of rural networks, although access was very limited.
After 2000, many villages jumped directly to mobile telephony, without ever having had a modern fixed switchboard.

📖 Annex III – Comparative tables of telephone exchange technologies

1. Evolution of switching technologies

Technology	Dominant period	Working principle	Advantages	Disadvantages
Textbook	1878–1930	Operator connects cables manually	Simple, flexible	Slow, expensive, lack of privacy
Strowger (Step-by-Step)	1891–1970	Step-by-step switching based on electromagnets	Remove the operator, automation	Noisy, bulky, heavy maintenance
Crossbar	1930–1980	Vertical/orizontal bare matrix cu contact	Fast, reliable, large capacity	High cost, space consumption
SPC (Stored Program Control)	1965–1985	Software call control, also analog/digital switching	Flexibility, new services	High complexity, difficult transition
Digital (PCM/TDM)	1980–2000	Voice to bits, time multiplexing	High quality, multiple services	High costs at the beginning
IP/Softswitch	2000–2020	Voice over IP, control via software	Scalable, cheap, data convergence	Initial quality issues, security
Cloud-native / 5G Core	2020–present	Cloud virtualized functions (NFV/SDN, IMS)	Scalability, integrated services, AI	Cybersecurity, vendor dependency

2. Call Quality Comparison

Epoch	Voice bandwidth	Perceived quality	Stability
Textbook	3–4 kHz (analog brut)	Medium, with jamming	Highly variable
Strowger	3–4 kHz	Medie, electromagnetic noise	Acceptable
Crossbar	3–4 kHz	Hello, less noise	Stable
Digital PCM	64 kbps/canal	Very good, standardized	Stable and predictable
VoIP	Variabil (8–64 kbps)	De la slab la excelent	It depends on the internet
VoLTE/VoNR	12–24 kbps advanced compression	Excelentă (HD Voice)	Very stable

3. Power plant capacity

Central Type	Max. number of subscribers (typical)	Connection Time
Textbook	50–500	10–30 seconds
Strowger	10.000–50.000	5–10 seconds
Crossbar	100.000+	<1 second
Digital E10/AXE	1.000.000+	Milisecunde
Softswitch	Millions (scalable)	Milisecunde
Cloud-native	Virtually unlimited	Milisecunde

4. Costs and maintenance

Technology	Initial cost	Maintenance	Necessary personnel
Textbook	Reduced	Elevated (Operators)	Dozens of operators/boiler
Strowger	Medium	High (mechanical)	Specialized technicians
Crossbar	Elevated	Medium	Electromechanical Engineers
Digital PCM	Elevated	Reduced	Electronics Engineers
Softswitch	Medium	Very low (software)	IT Administrators
Cloud-native	Variable	Automatizat (AI, software)	Network and Security Engineers

5. Romania in an international context

Period	Western Europe	Romania	Difference
1930–1940	Crossbar	Strowger/Partial Automation	5–10 years
1950–1960	Crossbar + SPC Start	Crossbar Pentaconta	5–10 years
1980–1990	Digital PCM/TDM	Crossbar in the majority	10–15 years
1990–2000	Complete digital	Accelerated digitization (E10, AXE)	5 years (recovery)
2000–2020	IP, IMS, VoIP	IP and GSM explosive	Synchronization with the West
2020–2025	5G, Cloud-native	5G, Cloud-native	Synchronized

📖 Annex IV – Diagrams and examples of operation

1. How a manual boiler worked (1880–1930)