Beware, as many of the new(er) T-mobile devices come with an IM client that doesn't use GPRS but SMS...

Take for example the new ipaq 6315; it comes with a GPRS modem AND WiFi, but it's IM client still uses SMS, making it much more limited AND you show up as a "mobile user" to other AIM users, and some users don't see you at all.

I'm warning you because unless you have a text messaging bundle you will be running up 5 cents per message in charges.

Just logging onto AIM can take as much as 3 or 4 messages, plus more every time someone logs on or off.