I ended up setting a support chat with Google tech and the lady advised clearing the phone cache.
Done that but not sure that's the fix, she'll have to try it and see as it appears to be a very random thing.
She also mentioned it only happens on local-ozzie calls. Never happens when on overseas calls when she can be talking for hours without interruption.
If not the fix we now have a case reference to get back in touch.
I'd be surprised it's the fix as some on the Google support forum were quite cluey and that seems to be a very basic solution to a problem that old and widespread.
Done that but not sure that's the fix, she'll have to try it and see as it appears to be a very random thing.
She also mentioned it only happens on local-ozzie calls. Never happens when on overseas calls when she can be talking for hours without interruption.
If not the fix we now have a case reference to get back in touch.
I'd be surprised it's the fix as some on the Google support forum were quite cluey and that seems to be a very basic solution to a problem that old and widespread.