Why do my calls fail every 2 hours?

[iMore Question]

Lately (as in everyday for the passed two weeks), my calls have been dropping and the message that pops up is "call failure". I always thought that it was bad reception as my boyfriend has quite poor reception in his area. I recently noticed though that the calls are only failing once I've hit the 2 hour mark of talking. I am in a long distance relationship so I'm calling from NZ to Aus if that has anything to do with it. It only started happening once I switched carriers when I got back to NZ 2 weeks ago. Is this happening to anyone else? How can it be fixed?

 

[kch50428]

http://forums.imore.com/ask-question/319759-my-calls-keep-dropping-due.html