Which phone do you have ? Did this just started happening? 'll leave a Link to register so you can communicate here as a guest account you can only post questions but can't reply.https://forums.androidcentral.com/showthread.php?t=409154
Check with your carrier. If they're sending you an "Unknown" carrierID, that's what will show. (I'm sure they'd want to know if some of their equipment is down.)