As was mentioned, POTS is Plain Old Telephone Service. For any youngsters out there, these are the older phones which had a telephone wire that plugged into a telephone port in the wall. They don’t have a normal electrical plug. They get their power from the telephone line. The telephone wires are run independently from electrical lines. If a telephone wire stayed intact during the collapse, it’s possible that an older style phone is still getting power. I would expect that the responders would do stuff like cut off electricity and gas for safety reasons, but they wouldn’t really need to worry about the telephone lines. They have such little power on them that there’s no real risk of getting shocked.