It sounds like you are on pre-paid. While that shuldn't make any diff. whether you have signal or not -- it seems an inordinate amount of "problems" postd here are from prepaid users.
I think pre-paids would be better off on systems solely geared to handle that type of account. The mainline carriers added prepaid service as an afterthought. I hope TM, for its own benefit, tsfrs. its prepaid customers to its newly acquired MetroPCS.
It doesn't happen often - but evry carrier does have outages.