MM SIM 1 NOT ALLOWED

[Mphathi]

Hi. I can't receive or make calls. Phone is saying MM SIM 1 NOT ALLOWED but SIM 2 slot is working. I've tried everything. S21 ULTRA.

[ThamiK]

Your phone has been blocked, it will take CellC on sim 1 and Sim 2 will take all sim cards

[Mbosh]

Check it could be carrier locked, try stopping the simcards, using the carrier from which you brought phone from on sim 1

[Nash4321]

Me aswell, same phone, same issue, let me know if u have found a solution

[Pacer73]

Still experiencing this issue on a S21+; I contacted Samsung but none of their suggestions worked. I noticed that sometimes MTN is working on SIM 1 slot for minutes or hours, then it stops working