CANNOT RECEIVE CALLS FROM OTHER NETWORKS😡😡😡

Good day

I have a problem with my MTN NO. ***, SIM CARD NO. ***.

I have tried to get help numerous times but no one is able to help me,,Ive called Customer care a dozen times, I even went to MTN STORE in Galleria Mall Durban but I have not been assisted. The problem is that I cannot receive calls from other NETWORKS,,,it goes straight to Voicemail. I can only receive calls from any MTN Number. Now this really fustrate me as Ive tried everything, every code I was given but no one is able to help me. I really do not know what to do anymore as this number is very important to me and Ive had this number for many years. Im losing on lot of important calls that are not from MTN network. I have NO Call Barrings,,,this number is active, I even did a Sim Swap but still I cannot receive calls from other networks And I even took out the sim card and used another phone but still.

Please help me.