Error 1635, iTunes could not check for an update to the carrier

Have the same problem. Message of mine is in Dutch. My phone is since ios5 upgrade just like yours unstable and especially i have problems with the button. And i'm pretty sure that there is not a button problem.

Read somewhere to do a reset instead of an upgrade. Will try that this evening. If it helped me out i let you know.

I am getting error 1635 after i factory unlocked my iphone via itunes. Not able to check updates from itunes due to this error. I restored my iphone twice but error 1635 is still there.

any solution?? I have iphone4s (GSM)

found solution here,,http://www.unlockit.co.nz/unlockit/ load the page using your device ..