There are several Mobile Phone Network in Nigeria and some times it is difficult to choose which is good for you.

All the network carriers in have many prefixes or access codes. The most difficult situation is trying to identify one from the other. One mobile phone network can have more than one access code. Remembering which is which is a tough ask any time any day.
In Nigeria the most popular mobile phone network are Airtel, MTN, Glo Mobile and EMTS Limited (9Mobile). All of them have at least 5 prefixes or access codes.

This article is meant to provide a list of all the major mobile phone network in Nigeria and their prefixes. It will serve a reference for you. When or if you want to sent virtual top up (VTU) or sent a recharge card gift to friends and family. It common to hear people asked in Nigeria “which network(mobile Network) are you using?”. This article will help identify any access code or prefix.

NIGERIA MOBILE PHONE NUMBER PREFIX OR ACCESS CODE LIST
Prefix Network
0701 Airtel Nigeria
0702 Smile
07025 Visafone
07026 Visafone

Kindly visit the site for the details....
https://www.infocontemporary.com/2018/11/13/nigeria-mobile-phone-network-prefixes-and-calling-format/