That is absolutely correct. A phone in weak or no signal area will use max power to try and find a tower, draining the battery rapidly. That isn't just WM phones or other fancy ones, it is any cell phone.
I work in a shielded building where we get no signal whatsoever, and we are not even supposed to have the phones in there. Occaisionally someone forgets and is typically rewarded with a dead phone by the end of the day.
My recommendation would be to put the phone in flight mode, if you are in an area with very weak or non-existant coverage.
(just read mike's post. saw the original and just hit reply without looking at the other responses. Guess we agree

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