I am with Telstra and don't know why but every now and then (around every few weeks?) the internet connection on my iPhone 5 would hung and wouldn't response at all.
When it first happened a while back, there's really bad storm outside and I have to call Telstra help desk for help. The instruction I received was to shut the phone down completely and turn it back on 30 seconds later.
Since then it happened quite a few times already. Not sure if it's Telstra issue or iPhone issue, and wonder if anyone having similar issue as well??