Miguelho,

Planning bandwidth for Voice calls require an understanding of the bandwidth requirements of the voice codecs that will be used for call processing.

With G.711 each call will use 80Kbps and depending on the layer 2 overhead could be more. Eg for frame-relay it will be 84kpbps/call and with ethernet it will be 93kbps/call.

So If you have a centralized site with your call manager in the HQ and agents in remote locations, what you need to consider is what codec will you be using to the remote locations. If you are using G.711 over the wan then as explained above each call will require about 84kbps/call.

So depending on the number of agents/site..eg if you have 5 agents/site with 4 sites, in all you will have 20 agents.

Lets provision for a peak period where all the agents in all sites are busy and we are using G.711, then we will have 20 agents X 84kbps (assuming you have a frame-relay circuit to the remote sites)

This equals 1680Kbps...For each individual sites at peak period you will have 420Kbps of bandwidth.

You can then configure your WAN link for this requirement.

If you are using G.729 across the want to the remote sites, then for each call G.729 will use 24Kbps, also depending on layer headers it caould be more..eg with frame-relay= 28kbps/call.

HTH