One way calling after 5 to 10 minutes

I live on the San Ramon and Dublin CA border and for about 10 months now, our Xfinity Mobile phones have started to have one-way audio after 5 to 10 minutes when starting a call with someone or someone calls us (We can hear the other caller but they cannot hear us).  The call then fails.  This has happened with iPhone XR, iPhone 12 Pro, and iPhone 13 Pro.  This seems to be a cell tower issue as when we leave the area, we do not experience the issue.  It only occurs around our home.  We assume this is a Verizon tower problem, but are unsure how to report it since it is Xfinity Mobile.  Please advise?