Hi Tom:
I have MANY unanswered questions with respect to the Microcell; and, Cisco will not answer (i.e. supported by AT&T) even though tier 2 Business Data Support is unable to assist at AT&T.
What I CAN suggest is the following: I have a bandwidth manager (free no charge/freeware) and once you install it, in addition to the icon in your tray/right side, you can right-click on the taskbark and "add" the "networx desk band" which is a real-time graph/you can see how it "spikes" during a call etc.
This software is available from the following site/vendor:
http://www.softperfect.com/products/networx/
I hope this helps :-)
James