Installation and Reference Manual
System Architecture
Installation and Reference Manual v3.2/0410/6 17
Although communication peers (eg phones) pass the voice data directly between them, the Gatekeeper
will control all of the call routing. The Gatekeeper therefore does not require high performance data
capabilities.
The Call Server runs Gatekeeper functionality.
Trunk gateways are registered with the Gatekeeper and act as a resource for the Gatekeeper to route
calls to and from the public PSTN networks. Trunks can be on physically separate modules and
geographic sites.
Clock synchronisation is performed by a combination of buffering and “Clock Count” signalling between
the master system and all slaves.
Call Servers and Trunk Modules run Gateway functionality.
Distributed Phone Modules
As each Phone Module is LAN connected it can now be distributed geographically within a building or
separate buildings and will only require one cable between the module(s) and the administration system.
This is particularly useful when wiring different floors of a building; only a small number of vertical risers
are needed. Each 100 Mpbs FDX Ethernet connection is capable of handling between 390-780 concurrent
calls, assuming no other traffic. Where non-QoS (Quality of Service) Switches are deployed then it is
recommended that Voice be separated from normal LAN traffic, each Call Server and Trunk module
contains a QoS Switch to allow such segregation. In normal circumstances (simple telephony) it is
recommended that the Ethernet cabling be treated as a new generation of flexible voice cabling and
independently connected, especially with the use of structured wiring and patch panels.
Because each Phone Module is geographically independent so is the Phone oriented computer
telephony. Each Phone Module is responsible for its own handling of a third party TAPI interface.
Additionally the central administrator can have first party telephony ports via TAPI.3.0 and H.323. This is
the method used for external voicemail.
Because voicemail utilises H.323, voicemail platforms can be operating system independent and located
in any appropriate location. Because of the multi-port registration philosophy voicemail can be spread
across many machines increasing the potential capacity of the system. This is especially important when
SAPI (speech recognition) is required.
Call Servers are capable of running an Auto attendant and voicemail service as standard. Voicemail can
also run on a Linux server and will handle storage limited only by the disk space of the machine (approx
0.5 Mbytes per minute).
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