authentication code cannot be verifed : message 16 switch 237

[Thinkpad21]

Hi, Got an HTC 6800 from Bell Canada that I have updated the rom to 3.35.651.2 from Sprint, but today I'm in the states ( Orlando Florida ) for the first time since the ROM upgrade and when trying to make a call, I get : Authentication code cannot be verified : message 16, switch 237.

Can anyone help... I have seen couple of threads on this site, but all of them talk about ALLTEL, but I'm with Bell Canada, what should I do, should I call my carrier, if so, what do I tell their support that would probably not know what to do...

Any help would be great, since I'm stuck...

Thanks very much !!!