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New Member

if pvdm is necessary?

i want to use 2811 to support voip.

i have already update the ios,then if i must install pvdm.or not it is just improve performance


Re: if pvdm is necessary?

You will need DSP resources if you want to support conferencing, transcoding, or media termination on the 2811. A PVDM provides DSP resources. You can use the DSP calculator below to determine the DSP resources necessary based on the network modules you will be using (FXS, FXO, T1/E1, etc) as well as your need for other services (conferencing, transcoding, etc). The PVDM link below describes the different PVDMs and the DSP resources they contain.

DSP Calculator

High-Density Packet Voice Digital Signal Processor Modules

Hope this helps. If so, please rate the post.


Re: if pvdm is necessary?

Any time you interface a TDM interface to the router to convert TDM signals to packets and back you need DSP resources. If you connect to a PBX or Telco and then convert those analog/digital signals to packet and back, will require a DSP. A t1, e1 , fxs, fxo interface on the router will utilize a DSP resource to do this conversion.

New Member

Re: if pvdm is necessary?

I was wondering about this myself. You said you need a DSP to convert to carry over a T1. I assume you only meant a PRI. Since it is already IP and if you go to a WAN interface I am thinking you don't need a DSP.

Hall of Fame Super Silver

Re: if pvdm is necessary?

Well, for PSTN connectivity such as T1-PRI you will need PVDMs as it is conversion between IP to TDM (Gateway). If all you have is WAN connectivity between sites then you will not need PVDM, however unless you have SIP trunks integrating you with outside world you have PSTN Gateway connectivity somewhere.