Hello. I am curious as to how carriers know when a tower stops operating other than from alot of users calling in to complain? If their was an RF problem on the tower or the antenna was damaged or whatnot, how would carriers know about such? I happen to have a cellphone with Sprint PCS. I used to get consistent 4 bars coverage year round. Now it is 0 bars coverage and I get signal fade in various locations throughout the community. This has gone on for a few weeks now at least. I reported the problem just recently so hopefully its resolved whatever the issue is. I probably am picking up the next tower past the one that usually worked for me. But Im just curious if it is a tower problem, if there is any sort of detection mechanism in place to tell before customers start complaining that the problem is there.