No actual calls come through

I am using two devices, android with graphene os and an iPad. I have six sudos, of which I use one daily for friends and family calls, the others rarely receive incoming calls, so I never noticed that all calls except the friends and family sudo go directly to voicemail when an incoming call comes through. Some allow me to pick up on the first ring, but if I’m not fast enough, the call goes to voicemail. 

this is VERY frustrating, especially when giving the number to a company with the expectation of an immediate call back that I never am able to answer. 

I really would love for the issues I am experiencing to be fixed, but what has happened so far are “fixes” that don’t fix anything. Please help. Thanks