Default No sound through the speaker on out going calls?

Hi all,

Had this problem for about a week now.

When I make an out going call, I hear the other side for 3 seconds and then the speaker cuts out. They can hear me fine.
The only way I found to fix this is to reboot the phone, it then works for a while before the problem come back.

I'm running a completely stock rom on 4.4.2 I haven't even rooted it yet (in case it has to go back).

I've had the G2 a few months and this started just over a week ago.

Any thoughts? Root and custom rom, or send it back and try a new unit??