Default [Q] Top speaker quality in viber

Hi,

I was using my old Galaxy s3 to call & txt fiance using viber in states, now that I have sold it to mazuma mobile I have used viber to call her for the first time on my z2 & I could barely hear her at all on the top speaker & had to put phone on speaker phone just to hear her , normal call quality is pretty good on mobile calls, volume was up full. She could barely hear me as well, I turned off noise cancellation in call settings & she could hear me a bit better but said it was still quiet.

Just wondered if anyone else has experienced this?

Cheers.