I have never heard of a device that could do it, and could not find one when looking now. Do you have more info. I assume that the only way that this system would work it would have to be able to hack into the phones signal, and or company.

In order to locate a phone you would have to trianglate the phones signal from the 3 most local towers in the area without being local to them already. I can't image that this could be easily done.