Polycom Vega Gateway - Manual (Page 20)

Version 2.1 16 March 2006 Page 20 of 33
Vega Gateway Scenarios. ©2005-2006 VegaStream Ltd.
Examples are given in best faith – ensure that you check the capabilities of systems before
deploying them, especially the functionality of devices not designed and delivered by VegaStream.
8. Leased line eliminator for QSIG connections between sites
Aim: To save leased line call costs between sites
In larger companies, the PBXs on multiple sites may be linked together via leased lines and using
QSIG signalling in order to make the distributed PBXs function as though they were a single PBX.
When linking PBXs together in this way, point-to-point connections are required between each
and every PBX. This becomes expensive in terms of leased lines.
By using the existing company IP network and Vega gateways that support ‘tunnelled’ QSIG, the
leased lines are no longer required. The Vega gateways receive the QSIG information on their T1
or E1 interfaces – then, using the destination information in the QSIG header the Vega can select
the correct far end Vega gateway to send the ‘tunnelled’ QSIG data to. The far end gateway
unpacks the received ‘tunnelled’ QSIG messages and presents them on its T1 or E1 interface.
The PBXs do not know that the QSIG connection was not a leased line.
Telephony Network
• E1 ‘tunnelled’ QSIG signalling is supported by Vega 400 and Vega 100
• T1 ‘tunnelled’ QSIG signalling is supported by Vega 400 and Vega 100
IP Network
• Recommend – private IP network between sites
• Can be any reliable IP connection, including leased line and line of site laser / wireless
connection
• Satellite IP connectivity is a possibility, though a system like this should be tested to ensure
that QSIG timeouts are not exceeded by the satellite latency.
• QOS should be implemented to ensure that VoIP packets pass through the network in a
consistent and timely manner and are not discarded by congested routers
• For inter-site operation the Internet can be used, but contention and available bandwidth
must be considered
VoIPon Solutions www.voipon.co.uk [email protected] Tel: +44 (0) 1245 600560