Since the 081 craze began, not always easy to tell which network a number belongs to. Many people cannot reconcile the new gen prefixes with a particular network. A number with the 0817 and 0818 prefix could easily be Etisalat or Airtel. In the era of the 080’s and 070’s, things were a bit easier.
Now a couple of guys got together to create a comprehensive list hosted on @olibenu‘s Github repo that clearly distinguishes between all these confusing numbers prefixes.
MTN
ETISALAT
GLO
AIRTEL
Hopefully, this would lessen the confusion, the accidental airtime overuse and help you navigate the 081 craze.
PS: Remember Mobile Number Portability became effective about a year ago. You might want to consider the possibility that some numbers prefixes may have ported out of their corresponding networks. The chances are pretty slim though.