Well, according this this thread:
http://www.blackberryforums.com/blac...em-laptop.html
The APN setting for T-Mobile should be:
TMOBILE USA Users (Success!)
+cgdcont=1,"IP","wap.voicestream.com"
And in order for Ramble IM to work, the only APN setting that works is wap.voicestream.com. Does anyone else have any input on this?