This is one of those problems that seems to have endless reports, but no clear solution. My phone is an iPhone 4S 64GB running iOS 5.0.1. My carrier is Optus in Australia.
Other problems that occur when the stuck End Call screen issue arises seem to be (for me anyway):
- No incoming SMS
- Can’t call out
- People calling in hear a your number dialling, but your phone does not ring.
I will run through my troubleshooting steps.
Some people believe it is a carrier issue, and you perform a carrier update if one exists. To do so, go to the About screen on the iPhone. Provided you have some sort of data connection, if there is a carrier update available, a prompt will pop up asking you to update. This did not solve my problem after updating.
It can be an iOS issue, but again I am running the latest. You can always upgrade and see if it sorts your issue.
It can reportedly be an upgrade issue, where you have kept the same settings from upgrading phones (ie. you have migrated from a 3GS to 4 then to a 4S). This was not applicable in my case, as I started fresh. You can try to setup your phone from scratch or factory reset. I’m skeptical of this fix, because a factory reset seems to fix everything, but the problem will probably come back due to an underlying issue.
The fix for me was to turn on mobile data, and then turn it off again. I leave mobile data off at all times, because I like to control when and how my data is used. There seems to be a bug with iOS when the phone runs for prolonged amounts of time with no data capability.