how do you get a mobile network carrier registered with apple

I have check on wireless network providers list for both iPad and iPhone for Zimbabwe and my network provider NetOne is not listed, what does this mean and at the same time how can they get added to the list.

I have also noted that a number of times data services on my iPhone 13 will not be working whilst on my Samsung S22 they will be working, is there a chance that this is related to the issue of my network provider being recognized by apple as a mobile network carrier