Shared plans and cannot hear caller and caller can't hear me

[BGcell]

I have a family plan with 2 lines, using Samsung 8 and iPhone 7 phones. Recently, we discovered that we cannot hear each other when making calls to each other. Our calls connect and the time keeps running but no sound on either end (phones aren't muted either). We can text each other without problem. We can make and receive calls with no problem with others. We tried to use the troubleshooter but we still couldn't determine the problem (bluetooth off).  Any help would be greatly appreciated. Thanks.