Can't talk or hear people talk in calls.

[uklele12345]

I noticed that when I get or call or when I call somebody I cannot hear the person taking and they can't hear me either.

 

[STARGATE]

If your volume and sound settings are okay in your device and a restart won't help. Get in touch with your carrier, it might be on their end.
If the phone is new and its been doing that since you got it, return it.