problems following latest update

Is anyone else having problems since the latest update?

I am having problems with my phone going to voice mail and not ringing and I keep having to reset the network. I have reset my iPhone 4 to factory settings three times now and have done countless hard resets to no avail. I have been on line to my provider and they don't have any problems with coverage in my area. I have no idea what to do now. I would appreciate any feedback.
Alison

Only problem I'm having is when answering my phone it will go to my cars bluetooth even when sitting in the house and the car is off.

does it direct calls to voicemail at random, or does it happen with every phone call?