There has to be some variance from one BB to the next. My daughter and I each have 8320's on Tmo on the same family plan. We each have Tmo Linksys routers. Our 8320s are both on 180 OS. She has a jawbone that works perfectly for her making UMA calls at her place and at mine. If I try to use her Jawbone on my 8320 I get booted to EDGE immediately at both locations. I've gone through both 8320s and the settings are nearly identical.

The only difference that I am aware of is that her 8320 is a few months newer than mine (based only on date of purchase).