PBX to PBX trunk over E3

Unanswered Question
May 5th, 2008


I'm new to VoIP and would like some advice:

Two of our sites have a dedicated E3 connection between two 3845 routers (IOS Version 12.4(3e)).

The connection is currently used for data only but it is not fully utilized and we would like to use it to send voice traffic between the sites also. The plan is to connect the PBX at each site with an E1 ISDN Primary trunk to the router at the site.

The router will send this voice traffic in IP packets to the other site over the E3 connection.

What card do I need in each of the routers (there is a HWIC and NM slot available in each)?

What are the commands to set up the interface card to packetize the voice traffic on one end and de-packetize it on the other?

A LLQ will be setup for the 2 Mb/s E1 voice traffic on the E3 connection.


I have this problem too.
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Paolo Bevilacqua Mon, 05/05/2008 - 19:51


you need vwic-1mft-e1 or vwic2-1mft-e1/t1, plus pvdm2-32. For the configuration, look on CCO for "pbx pri", it's quite simple. Usually best results are when you pbx support qsig protocol.

Hope this helps, please rate post if it does!

jeffland_98 Wed, 06/11/2008 - 09:34

Actually there is a card which does exactly what I wanted: NM-CEM-4TE1

It does circuit emulation of either T1 or E1 circuits. The routers just sends the links through between the PBXs. It's alittle bit expensive though.

Paolo Bevilacqua Wed, 06/11/2008 - 14:56

Indeed, CEM it's more expensive and doesn't bring the advantages of voip: bandwidth used only when there are active calls, flexibility in routing numbers around, and too many other things to mention.


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