[cisco-voip] Send outbound calls from a specific port to a specific port

[Joseph Mays]

Have a customer with a Cisco IAD. They are using VOIP for most calls, but 
there is a fax machine on port 2/7 and they want that to use a dedicated 
phone line, so we have two channels of the T1 assigned to being a PRI with 
one channel. This works fine, and it's easy enough to direct inbound calls 
to the fax number to port 2/7. The problem is with defining dial-peers for 
outbound calls.

Basically, they want all calls to any number out to the world to go across 
the SIP trunk -- which is fine, easy, and currently working. But they want 
calls to any number from port voice 2/7, where the fax machine is plugged 
in, to go out the PRI. I'm having real trouble defining a set of dial-peers 
that works properly. Everything I define results in the dial-peer for 
outbound voip grabbing all calls out to the world.

How does one define a set of dial-peers that say "All calls to other numbers 
go out the SIP trunk, EXCEPT calls from voice port 2/7, which should go out 
the PRI trunk?" Currently I'm doing it by using translation profiles to 
append a special number to the beginning, then routing calls with that 
number out the PRI, but that feels jerry-rigged and it seems like there has 
to be a better way to do it.