is used, the significant digits are prepended to the DNIS number, and a SIP
Proxy can be configured to route calls based on those prepended digits. The
static routes in the SIP Proxy for the VoiceXML Gateway should have the digits
prepended. Because these prepended digits were originally populated by the
Ingress Gateway, the SIP Proxy can use them to determine which VoiceXML Gateway
to use based on the incoming gateway. In this way, calls arriving at a
particular site can always be sent back to VoiceXML treatment, with the result
that no WAN bandwidth is used to carry the voice RTP stream. The Unified CVP
indiscriminately prepends the
value to all transfers, including those to Unified CM. Therefore, when using
Unified CM in this scenario, it is necessary to strip the prepended digits when
the call arrives, so that the real DNIS number of the phone can be used by
Unified CM to route the call, as illustrated in the following example.
The configurations mentioned below are only applicable to IOS Voice
Configuration of Ingress Voice Gateway:
translation rule to the incoming DNIS to prepend the value 3333:
rule 1 8002324444 33338002324444
dial-peer voice 1000 voip
translate-outgoing called 99
the DNIS number is 8002324444, the final DNIS string routed to Unified CVP is
Configuration of Unified CVP SIP service:
configure the SIP service, in the Operations Console, select
Call Server >
SIP. Many of the settings are in the Advanced Configuration window.
the Voice XML Gateway to match the DNIS string, including the prepended digits:
dial-peer voice 3000 voip
incoming-called number 33335551000T
the Unified CVP bootstrap.tcl application with the
parameter, indicating how many digits to strip off of the incoming DNIS string:
service bootstrap flash:bootstrap.tcl
param sigdigits 4
Unified CM configuration (if used):
Unified CM to strip the prepended digits, either by using the Significant
Digits configuration on the SIP Trunk configuration page or by using
static routes on the SIP Proxy, with the prepended digit present, to be sent to
the appropriate VoiceXML Gateway. Because transfers to agents on a Unified CM
cluster have prepended digits, the static routes for agent phones must also
contain the prepended digits.
of call routing:
A call arrives
at Unified CVP with a DNIS number of 33338002324444.
removes four digits (3333) from the beginning of the DNIS string, leaving
8002324444 is passed to ICM for call routing.
When it is time
to transfer, ICM returns the label 5551000102. Unified CVP prepends 3333,
The SIP Service
then resolves the address using the SIP Proxy or local static routes, and it
sends the call to the VoiceXML Gateway.
Gateway bootstrap.tcl removes 3333, leaving 5551000102 for the destination