[cisco-voip] Seeing active calls over a WAN link ?

[Tech Guy]

Any ideas on how I might be able to determine or see active calls over
a wan link?  Basically we have 5 remote locations, all with T1's and
Cisco 2621 routers.  These locations have about 15 users, with
7940/7960 phones that connect back to the corporate office
CallManagers.

We appear to be having some BW and/or QoS issues according to what we
see on the router, and on our solarwinds monitoring software.

However we dont seem to have a good way of knowing how many phone
calls are going across the wan at any given time.  I tried using
attendant console and grouping all the phones and watching the line
status but I question if it is working correctly because I only see
person on the phone, yet qos says we are utilizing like 400Kb of voice
payload traffic according to the 5 min. stats.

Any ideas on better tools for troubleshooting and helping to get to
the bottom of this?  Especially something to see the number of calls
across the wan to a  specific remote router location?