So can you put SIP credentials into the phone and us it for VOIP or is WiFi only for browsing and data delivery?

I don't believe there is a SIP client yet for the 8320/8820. And since apparently AT&T does not support UMA, I don't know how to get calls over IP.

So is the WiFi just a high speed gateway to the Edge/GPRS netowrk? I would have assumed once you went WiFi you were free from the contstraints of the carriers network, almost completely. Maybe I'm not understanding your point.

You never completely escape the carrier. UMA (the voice of WiFi piece) takes your voice call over WiFi and hands it to the carrier. T-Mobile still knows about it and charges you. There is no free voice client (yet) for the BB. AT&T does not support UMA at all.

Total bummer...

A SIP client will only appear if RIM releases the Voice APIs for the phone. I dont know if that has or will happen. Does anyone know?

edit

Correct; there are several posts (from yesterday) with the complete rates for both International and Domestic calling with and without H@H.

edit

As far as I could tell if you swithch the browser setting to wi-fi, then the carrier does not know about the data being transferred. The data transfer is between the BB ans the router directly. feel free correct me if I am wrong.