No sound on first call, always works on second

I get no sound the first time I am calling someone else, but they can hear me. But, it always works on second call. I have an iPhone 6 Plus. I tried it with wifi calling off and problem was not resolved. I also turned off call on iPad and MacBook Pro when available. Still no help. Others report similar problems. But, it's rare to hear of someone who consistently has a problem on their first call and not on their second.

Vince