Polycom Vega Gateway - Manual (Page 3)

Version 2.1 16 March 2006 Page 3 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.
Telephony Network
• E1 Euro ISDN signalling is supported by Vega 400 and Vega 100
• T1 NI1 & NI2 signalling is supported by Vega 400 and Vega 100
• T1 Loop start, Ground start and Wink start CAS signalling is supported by Vega 400 and
Vega 100
• BRI Euro ISDN signalling is supported by Vega 50 BRI
• Analog connection is possible, but is not preferred (for details on analog connectivity see
later section)
IP Network
• Recommend – private IP network between sites
• Can be any reliable IP connection, including leased line, line of site laser / wireless
connection and satellite
• 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
• Consider VPN between sites as this:
- removes any issues with firewalls / NAT
- encrypts audio and management data
• The Internet can be used, but contention and available bandwidth must be considered
User experience
• By grooming the traffic on the PSTN side of the PBX all user PBX functions will continue to
operate. This system will operate in exactly the same way as the phone system worked
before the gateways were installed, for example, even existing shortcode dialling will
continue to work (as the PBX will expand this to a full number before presenting it to the
PSTN).
USPs
• Vega dial planner capability provides powerful routing decision making. For example, calls
can be routed based on dialled number prefixes, full numbers, and even on who is making
the call.
Considerations
• Check the numbers that are presented to the PSTN consider for example:
- does the PBX present both National format and local format numbers to the PBX?
- does the PBX insert any “carrier select prefix” to the dialled number?
- can “block caller ID” or other prefixes be used in dialled numbers?
• Emergency calls should be routed directly to the PSTN, not over the VoIP link
• Program in fixed number length dial plans where possible to avoid the DTMF timeout
delays incurred when routing calls to variable length numbers
• Call transfer from PBX to PBX will only work if call transfer PBX to PBX worked across the
PSTN (the PBX may block this).
• If extension number dialling of the far end PBX is to be used (rather than just grooming off
the full dialled destination number), remember the extension number will have to be
prefixed with the PBX’s ‘connect to PSTN’ digit; usually 9 in UK, but can be 0 in Europe.
• If IP connectivity fails, calls can be programmed to be routed over the PSTN instead; there
may, however, be a bit of delay in deciding that the IP connection is down.
VoIPon Solutions www.voipon.co.uk [email protected] Tel: +44 (0) 1245 600560