I cant recieve calls from att mobile phones

I cannot recieve calls from ATT mobile phones. Whenever an att person calls me they get this message "Call cannot be completed as dialed, please hang up and dial again." I can text and make outbound calls to ATT customers.  I can't get the technical support people to believe me, they always send me a message saying there is nothing wrong with my phone. I recently ported my number from ATT.  Any ideas? Am I being blocked by ATT? I've been through the process of is your phone on do not disturb numerous times, nothing I can do on my phone can cause that error message. 

Re: I cant recieve calls from att mobile phones
Customer Service Rep

RandleKA, we want to make sure that you can get the best service possible. Is your device able or send calls or texts to the other service devices from AT&T? JoseL_VZW