NonprayingMantis: This is a pretty massive thing and the fact that this has, as far as I know, never ever come up before on this forum, (except when sbiddle's blog says the opposite is true) suggests that the most likely thing here is simply a misunderstanding and that the charges are for something else. Probably the rep on the phone doesn't understand either and is just guessing, or thought you meant you had put a phone divert to voicemail (so your phone rings, then sends to voicemail, which would likely incur a charge) rather than just switching your phone off, or maybe he thought you were dialling your voicemail to retrieve your messages, which would also incur a charge.

What I am saying is, surely somebody would have noticed this by now if it were standard practice since it would be so easy to rack up $1000s of dollars of fees without doing anything if somebody keeps trying your phone.

we see plenty of newspaper articles about excessive roaming data charges, but I've never seen one where the person incurred loads of charges from simply leaving the phone off