100 mins - 50 MTN and 50 to Any Network

It is very annoying that MTN do not even have the courtesy of advising that they have received an e-mail, they don't even bother to respond. My complaint relates to the minutes being split 50/50 between MTN and non-MTN networks. With numbers being ported these days how am I supposed to know who is MTN and who is non-MTN?