Hey all--to start with, I know this is not a BES question, but I am not finding consistent info from other forums, and I trust folks on this one more then others, so figured it cant hurt to post here.

A friend of mine is traveling to England next month for a week. She's trying to find the cheapest way to still be able to use her BB, specifically BBM. She is on T-Mobile and has gotten the phone unlocked. Will any international SIM with data work, or does it have to be BB specific to allow BBM to work? I've seen answers on other sites state that any sim will work, some that it won't; additionally on poster says if you have TMobile, just add their international plan for the trip and disable all APNs (under TCPIP Options on the device) and you won't incur any charges for BBM b/c it will use RIM's network only, and not the carrier's data network. That makes sense but, but I am wondering if anyone with experience in this can confirm that and/or share the best option for this. Thanks!