supersunbird
Honorary Master
"Roaming" is not the correct way of describing their relationship with MTN. Mobile operators who allow other network operator customers to use their infrastructure when the customers home operator does not have an infrastructure in place in that specific area to directly serve its customers is said to allow roaming. That roaming is based on a contractual agreement between the two operators.
What I deduce from what you have said is that FNB is a reseller of MTN services based on a contractual agreement between it and MTN. Subtle but there is a difference. In effect, you are moving from VC to MTN from a technical point of view.
FNB Connect is a VMNO. Only Cell C does VMNOs. Cell C now roams on MTN.