phone call to/from a specific person not going through.

I’m having a problem with my iPhone7+. Everytime my brother calls me and i pick up “call lost” comes on my phone and it hangs up, and when I return his phone call it doesn’t ring on his side, only I can hear the timing.... this has been going on for 4 days now. I’ve called Verizon they say there’s nothing going on on their end. Has anyone else had this problem? And how can it be fixed??? It’s sooo frustrating! I’ve tried resetting several times, blocking and unblocking his number, and so many other things. -help me please