If you have Sprint and move - check your bill very closely. We moved from Illinois to Texas to VA back to Illinois.
We have or had 4 cell phones on our Sprint plan. It was only after a few years that we noticed Sprint had been charging us taxes for VA long after we had moved to Illinois.
Several consecutive months of calls to Sprint, each time with a promise to fix the situation, FINALLY resulted in this monthly fee being removed. We have no idea how much we incorrectly paid for Virginia taxes when none of our phones were in VA!