why my phone is slow and stop working suddenly? I have moved to Malaysia recently. unfortunately my iphone 5s is working slow even sometimes when I press home button the screen stays black ( looks like switched off ) and I have to keep pressing home and lock button for couple minutes to get my phone back. or for example when I want to get out of an apps my phone freezed and stays like that for 10 seconds.
the available storage is 3.4GB and IOS version is 8.3.
Thanks guys
This likely has to do with your carrier settings. Have you gone to settings > general > about to check for a carrier update?

If you don't see "new carrier settings available" after visiting general, plug your iPhone into iTunes, and manually check for carrier settings.

The next thing would be to go to general > reset and reset your network settings.

If that does not work, back up your phone to iTunes and preform a full restore. This takes a while, but should eliminate most if not all stubborn freeze/slowdown issues.

If it does not, go to settings > general > reset and reset all settings. You won't lose data, but will have to set up your preferences again.