Home > CUCM, Gateways > Configuring Outbound Services via Alternate Trunks ISDN & SIP

Configuring Outbound Services via Alternate Trunks ISDN & SIP

Hey All

Have had a few questions around how you can determine which trunk a call leaves a customers environment, and how you can force calls through a particular trunk. This is very useful for customers who have multiple services but only have certain number ranges down each service, or if the customer wants to block CLI on one of the trunks and only send certain call out this one and the rest out one of the other trunks.

To set this up a few additional commands and dial-peers need to be configured on the relevant voice gateway to first locate the call with the correct calling number and then ensure it leave the system through the correct trunk to the carrier.

Using the Cisco IOS “answer-address” command this can be achieved

Usage Guidelines

Use the answer-address command to identify the origin (or dial peer) of incoming calls from the IP network. Cisco IOS software identifies the dial peers of a call in one of two ways: by identifying either the interface through which the call is received or the telephone number configured with the answer-address command. In the absence of a configured telephone number, the peer associated with the interface is associated with the incoming call.

For calls that come in from a plain old telephone service (POTS) interface, the answer-address command is not used to select an incoming dial peer. The incoming POTS dial peer is selected on the basis of the port configured for that dial peer.

First create some translation rules and then assign these translation rules to the translation profiles.

These will pre-pend a number for the incoming call to the gateway from CUCM in the below example this is 77 and 88 and remove the 77 and 88 including the zero (0) when it leaves the gateway and goes to the carrier

Note: Try not to use 99 as the prepending digits as this causes issues when you are then trying to strip the digits leaving the gateway

!
voice translation-rule 77
rule 1 // /77/
!
voice translation-rule 88
rule 1 // /88/
!
voice translation-rule 777
rule 1 /^770/ //
!
voice translation-rule 888
rule 1 /^880/ //
!
voice translation-profile PrePend77Incoming
translate called 77
!
voice translation-profile PrePend88Incoming
translate called 88
!
voice translation-profile Remove77Outgoing
translate called 777
!
voice translation-profile Remove88Outgoing
translate called 888
!

The below dial peers capture the calls based on their mask when leaving the CUCM system and matches on one of the below dial peers which in turns forces the calls out the relevant Trunks

dial-peer voice 77 voip
description === Outgoing Calls ALLOW CLI ===
translation-profile incoming PrePend77Incoming
answer-address 024321….
dtmf-relay rtp-nte h245-alphanumeric
codec g711ulaw
no vad
!
dial-peer voice 88 voip
description === Outgoing Calls BLOCK CLI ===
translation-profile incoming PrePend88Incoming
answer-address 029876….
dtmf-relay rtp-nte h245-alphanumeric
codec g711ulaw
no vad
!
dial-peer voice 1 pots
description === Outgoing Calls BLOCK CLI ===
translation-profile outgoing Remove88Outgoing
destination-pattern 88T
progress_ind setup enable 3
progress_ind progress enable 8
port 0/0/0:15
!
dial-peer voice 2 pots
description === Outgoing Calls ALLOW CLI ===
translation-profile outgoing Remove77Outgoing
destination-pattern 77T
progress_ind setup enable 3
progress_ind progress enable 8
port 0/0/1:15
!

Below is also a default dial-peer which has the standard destination-pattern 0T which captures any calls without a mask and sends them out the defined default trunk.

dial-peer voice 3 pots
description ==== Outgoing Calls Default ====
destination-pattern 0T
progress_ind setup enable 3
progress_ind progress enable 8
port 0/0/2:15
!
!

Enjoy

The Voice Man

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Categories: CUCM, Gateways
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