Hi,
Try the following and check if that resolves the problem:
a). Wipe the cache partition and then make a call on one of the apps (or all of them) and check if it now works OK
b). Start the phone in safe mode and then try if it works OK.
If it works OK when in safe mode then a downloaded app is the cause of the problem. The trick is to find out which one is the culprit. You will need to uninstall each downloaded app, one by one and test the phone in normal mode between each uninstall until it works OK. When it does the last downloaded app that was uninstalled was the cause of the problem. A downloaded app is one that you installed on the phone and was not already pre-installed when you first got it.
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