5- OmniPCX Office native VoIP
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Native VoIP
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Native VoIP 5-2
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Capacities 5-3
IP Telephony
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Capacities 5-4
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Fast IP enabler 5-4
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IP IP PIMpphony 5-5
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Benefits 5-5
IP Trunking
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Capacities 5-6
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WAN access methods 5-6
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IP trunking overflow and back up 5-7
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Interoperability 5-7
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Benefits 5-7
Bandwidth
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Voice Activity Detection (VAD) 5-8
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Bandwidth needed for a voice call 5-8
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OmniPCX Office mechanisms for bandwidth optimization 5-8
Native
VoIP
Based on the all-in-one
concept, Alcatel OmniPCX Office is natively IP.
It is capable to manage not only packet but also circuit world…with
unmatched voice features and applications.
OmniPCX Office is a native VoIP appliance. It
integrates a Ccall Sserver
and a Media Gateway and a H323 Gateway.
The Ccall
Sserver
is the OmniPCX Office CPU which runs on Linux
The Mmedia
Ggateway
is the combination of the different circuit trunk boards, circuit extension
boards and the CoCPU VoIP where the DSPs are pluged.
The Call server and Media gateway incorporated
H323 protocol to take into account standard H323 devices and interoperta with
Alcatel and non Alcatel systems supporting this standard.
Native
VoIP
DSPs (Digital Signal ProtocolProcessor) are
an important part of central system resources for VoIP They allow codings
and transmission between an IP phone (or Pimphony IP) and the ISDN/PSTN world (or a circuit extension
of the company). Those DSPs are located on the CoCPUVoIP.
Capacities
Up to 6 CoCPU VoIP per system
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Overall limit 96 DSP compression channels
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Nb of CPU+CoCPUvoip+CoCPU@ must not exceed 3 per main
module or extension module.
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A CoCPU VoIP supports provide connection for one
daughter board
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VoIP daughter board 4 DSP or
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VoIP daughter board 8 DSP or
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VoIP daughter board 16 DSP
Use of those DSPs is subject to channel/DSP
software keys
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key 2, key 4, key 8, key 16
If you need 10 DSP you must buy
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CoCPU VoIP + VoIP daughter board 16 DSP+ key 2 + key 8
In oder to define the number
of DSP for a given configuration, please refer to the automatic tool embedded
in the OmniPCX Office quotation tool (Actis)
It supports
Alcatel IP phones, H323 client software, as
Microsoft NetMeetingAlcatel PIMPhony IP edition and H323 clients
(as Microsoft NetMeeting). All these IP terminals have the same voice quality
as standard Alcatel Reflexes terminals.
includes several security
mechanisms to protect company network and data from external enemy and secure
internet accesses.
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IP subscribers : 200 (IP phones & IP PIMphony IP )
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Number of DSP channels :up to 96
Refer to the OmniPCX Office
quotation tool (actis) to define the number of DSPs needed for a given
configuration
This
plugware is an Ethernet LAN switch 10/100 base T.
It transforms an UA set into an IP set. It allows the company to use a single
port in the corporate LAN to connect the employee PC and telephone
Towards
the corporate LAN, it has an uplink which can be configured in 10 or 100baseT.
The UA
set is connected internally to one port of the switch. The PC is connected
externally to the other port of the switch which is auto-sensing and
automatically adapts to the PC configuration (10 or 100BaseT).
The fast
IP enabler is able to tag the voice packets at the level 2 (Ethernet)
using 802.1P and 802.1Q and at
the level 3 (IP) using TOS and DiffServ. When connected to OmniPCX
Office, only level 3 is used because in small SME configurations LAN
bottlenecks can usually be avoided.
The fast
IP enabler gives priority to the voice and voice signalling packets in the direction
of the corporateon the LAN.
The fast
IP enabler will choose dynamically the
best compression G711 when packets will stay in the LAN, and G723.1
when packets will be sent over the WAN, or G729a when requested.
PIMphony basic, Pro and
Team can be installed in IP mode on a multimedia PC. To do that the customer
must buy e PIMphony software keys. The Protocol stacks (identical to the one of
IP Reflexes) to put on the PC are in the PIMphony CD. They include G711 and
G723.1 voice compression algorithms.
Level 3 QOS is provided :
Microsoft Windows (98, 2000, Millenium, NT4) use TOS and will perform the
tagging of IP Voice & Voice
signalling packets in the PC. Those packets will have priority when sent by the
PC
Voice can then be
delivered through the PC microphone and Loudspeaker. An optional “IP handset
Comfort kit” is available in the catalog to provide increased confidentiality
and comfort to the user. This handset can be hung up by the side of the PC screen.
An alternative is a professional headset.
Moving, adding and changing :
With the embedded DHCP server, moving or adding an IPphone will only require plugging it into the new ethernet connection.
Adding an IP phone can be done either by pluging directly the IP phone to any ethernet port. If no ethernet port is available, the ethernet network is easily expandable by cascading a new LAN switch. Of course if the user already has an ethernet connection for his PC, this connection can be shared between the PC and the IP phone thanks to the IP plugware. In this case no supplementary Ethernet port, nor cabling is needed.
Branch office and Home worker solutions
Customers more and more request a transparence of features between Headquarters and Branch Offices (same directory, voice mail, features etc…). This is a standard feature of remote IP phones in the branch or at home, managed by the call server in the headquarters. The IP phones at the remote site have the exact features as they would at the company site.
This implies a managed data link between both sites (leased line, IPVPN…).
Mobile worker solution
Mobile workers usually don’t benefit from a managed data connection, but connect from time to time their multimedia PC to the company through the internet to download price lists or files. If their PC integrates VoIP (e.g. IP PIMphony), they can benefit remotely from telephony features on the call server.
IP
Trunking
Companies with “state-of-the-art managed WAN data network” are today
willing to mix voice and data on this network to save money on inter site
telephone calls. This can be done by sending voice over IP over this “managed
WAN data network”. These solutions are particularly popular with multi-site
businesses that call long-distance and/or internationally on a frequent basis.
Capacities
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IP trunks : 120
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Number of DSP channels: up to 96
Refer to the OmniPCX Office quotation tool (actis) to define the number
of DSPs needed for a given configuration
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For IP trunking, OmniPCX Office delivers not only
G723.1 but also G729a compression mechanism. G711 coding can also be used but
does not optimize bandwidth.
WAN
Access Methods
IP sets and IP phones managed by
the OmniPCX Office can access to the WAN through the OmniPCX WAN connection or directly through an external router.
WAN access through OmniPCX Office (refer to chapter internet)
-1- ISDN 2 B connection to an Internet Service
Provider. Either the 2 B channels from a Basic Rate Interface (BRA) or any 2 B
channels from a Primary rate Access (PRA)
-2a- Ethernet connection to any existing router (called dual Ethernet)
in R1.1
-2b- PPPover Ethernet (PPPoE) connection to an ADSL modem in R1.1
In those configurations, VoIP packets share the bandwidth with OmniPCX
Office internet applications (E mail, VPN, etc…if used ) and benefit from
OmniPCX Office WAN QOS mechanism.
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Policing : Based on TOS/Difserv header, OmniPCX put
Voice over IP in its high priority queue
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Queuing/ Shaping : OmniPCX Office manage 2 queues in
a buffer memory. High priority queue and Lower priority queue.
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Congestion control : OmniPCX Office use Random Early
Detection mechanism (RED)on the Lower priority queue to inform packet sources
to decrease their transmission rate.
IP
Trunking
Direct WAN access through router
Any existing router directly connected to the company LAN
In this configuration VoIP packets benefit only from the external
router QOS mechanism (if any).
Nota :OmniPCX Office internet applications (firewall,E mail, VPN,
etc…)cannot be used in such a configuration, therefore external devices will be
required for such applications.
IP trunking overflow and
back up
Whatever the connection method, OmniPCX Office offers ISDN Overflow and
Backup mechanism fully integrated with ARS.
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Overflow : when VoIP calls exceeds atreshold
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Back up : In case of failure of the WAN link
Interoperability
OmniPCX Office being H323 V2 compliant, is able to interoperate with
Alcatel and non Alcatel systems supporting this standard
International/Long
distance savings :By replacing « E1 tie-lines boards and dedicated voice leased
lines » between dispersed PBXs with « VoIP gateways and data leased
lines », multi-site customers can circumvent expensive telephone charges,
by using the data Wan infrastructure. A company can reduce long-distance
charges for intra-company calls by integrating voice, in the enterprise data
networks.
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Bandwidth
Voice Activity Detection (VAD)
In a phone conversation,
one party speaks at a time. The packets sent by the listening party are just
“silence”packets which spoil valuable bandwidth. The target is then to detect
the beginning of a silence, inform the other device (which will generate
background noise to avoid the impression of “cut line”)and stop emission. It is
assumed to decrease necessary bandwidth by 35%
Bandwidth needed for a voice call
·The
bandwidth needed for a voice call depends on a number of factors :
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Voice call transported on the LAN (Ethernet) or on
the WAN?
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Compression mechanism used : G723.1, G729a , none
(coding G711) ?
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Voice Activity Detection (VAD) used?
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Compressed Real Time Transport Protocol (CRTP) used
at the WAN access ?
(*) IP frame +
MAC (14) + CRC(4) + preamble (8)+ silence inter-frame (12), (nota :without VAD)
(**) 8 bytes layer
2 overhead (=max for PPP, MLPPP, FRF.12, HDLC)
(***) Some
Switch/routers are able to compress RTP/UDP/IP headers from 40 bytes to 4bytes
(or even 2 bytes in certain conditions). It is called Compressed Real-Time
Transport Protocol or CRTP. It brings the bandwidth at IP level down to 9 or
11Kb/s for speech transmission. OmniPCX Office can benefit from that.
(****) In the
table we have not taken into account bandwidth saved with Voice Activity
Detection. For information, VAD is assumed to bring down bandwidth needed at
65% of full rate.
OmniPCX Office mechanisms for bandwidth optimization
OmniPCX Office provides
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In the LAN, G711 coding and G723.1 compression
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In the WAN, G723.1 compression, G729a compression and G711 coding
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Voice Activity Detection
OmniPCX Office is fully
compatible with routers using CRTP
Easier management: For
corporations with multiple sites, management of PBXs is not
centralized.. As a result, IT managers can reduce the time and effort that they
spend managing the telephone system.