Alcatel phone. My friend can't receive calls from a few people on his contact list. It's a fast busy signal. He can call me. I tried entering the number, instead of using speed dial. I had him block/unblock me. I had him remove me from his contacts list and restart the phone. His daughter can't call him and one other person, that he knows of,can't call him. He's got a few who can.
Even when he turns it off, it's a quick busy signal.
Anyone have a troubleshooting idea?

Send it back and get another brand of phone ?

I use Tracfone  with a Galaxy. A-13 and it behaves good.  It's an older phone now but I've had it for years.