I don't quite understand this. My past experience with "BB BIS AddOn" using my Blackberry in China is that there is listed a tiny "Megabytes" item for each email access (almost never over 0.01 MB) but I never see a charge for this. I just talked to the T-Mobile customer service and asked how to explain the comments I have read above, and they said there has been no change in their service, and I should continue to pay only the monthly $19.99 for this AddOn.

Only once have I dared (as an experiment) to use the "GPS" map feature on the device, which clearly downloaded many MB of data. I expected to have a large charge of possibly tens of dollars, but none ever appeared.

Are the 4-figure bills mentioned in this forum using this same BB BIS AddOn or some other option?

My last visit was in June, but TMO says "no change."