Hi. My phone is not working in Rwanda. How can you help me?

Then, you will need to contact MTN to see if they can authorize your phone. It is possible that your previous carrier has locked the SIM card. If that is the case, then your previous carrier will need to unlock the card before MTN will be able to use the iPhone.

Sorry, we cannot help. You will need to contact your carrier to ask about whether they have an International Calling plan option that will work with your iPhone.

Please define “not working”.

This is too vague to be able to address.