Voice Gateway

Unanswered Question

We are in the process of converting a 2851 mpls router into a voice gateway. I know the 2851 has 3 slots for PVDM's and I figured I needed to put a voice image on it. This router is going to be handling 3 T1 Pri. It will also be an MGCP GW. What else do I need to consider when I am deploying this new voice gateway?

Also, I guess one thing I need to figure out is how the T1 pri's will go into the device...

I have this problem too.
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Nicholas Matthews Thu, 01/15/2009 - 11:31

This isn't all too difficult.

PVDMs will go on the motherboard, they look like RAM chips. If you're unsure on how many DSPs, use the DSP calculator:


Use this link to find an appropriate IOS image for your current feature set:


The T1's will go right into the router, something like a VWIC-1MFT-1T1 (or any of the other 5 variations).

You'll want to make sure you have this often missed command to prevent slips on your T1:

network-clock-select 1 T1 x/x/x

This is an incredibly helpful link for beginners:


Outside of that, MGCP is fairly easy to configure.



Thanks Nic for the fast reply I will check these links out. I guess what I should have also mentioned in this post is that we are in a situation where we need to take 1 3845 and separate it into 2 voice routers. Meaning I need to take the T1 cards out of the 3845 and put them into the 2851 router, but I am not sure if I need to purchase a vwic card to house the T1 cards if that makes sense. I need to leave the current vwic card in the 3845 so that it can still serve the FXS cards that are currently in the router. Thoughts?

Nicholas Matthews Thu, 01/15/2009 - 12:39

If you want two T1's on different routers you will need two T1 cards. You will also need two sets of PVDMs.




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