iPhone 4 problems

My wife tried calling me on my mobile and landline she could not hear me and i could not hear her. I have done numerous power offs and hard resets and also done a factory reset but it still won't work. The phone receives texts okay.

Any ideas?

Does the speaker work? e.g. playing music and does mic work if you do a skype call?

If yes, then probably just a network issue rather than the hardware in the phone dying.