Some users of the Lumia 630 are reporting bug in which the microphone and speaker of the phone don’t work during telephone calls.
A user based in Ogun State who got his device just yesterday said to me, “..it is frustrating my existence right now.” He made it clear that it isn’t a general problem, adding, “Another  owner, Dr Magnus, says he has no such issues with his. But there are lots of complaints all over the internet.”
According to complaints I have received and what I have read elsewhere online, only a hard reset has been able to resolve the bug when it manifests. It does not appear to be a hardware problem, since a reset temporarily solves the problem. There is a thread dedicated to the problem on Microsoft’s website: Nokia Lumia 630 Call Issues.
Is there anyone else out there who is experiencing this and has found a permanent solution to the problem?