Padders I am on BES. However, I have only been on BES for my most recent trip (South America). All the travel I did before that time was BIS & there have been no additional data charges.

Incidentally I disagree that T-Mobile doesn't know how much data we're using. My bill shows very clearly the data usage from each international carrier including multiple carriers within the same country. For example, in Brazil service kept jumping between GPRS, EDGE, and GSM depending where I was & I have three separate Brazilian carriers listed on my bill. No secrets here. And no additional charges.

I've been all over the world (recently to Canada, Iceland, Malta, England, Germany, Czech Republic, Romania, Austria, Peru, Easter Island, French Polynesia, Australia, Philippines, Cambodia, China (Tibet), India, Egypt, Morocco & so forth) with my bb and NEVER had data roaming charges. Huge roaming charges for voice calls yes; but nothing for data.

I hope this helps.

PS - I use the wap.voicestream.com apn.