Attached is a very old list I compiled over 3 years ago. It may probably help as you dig around for more recent settings

Some operators optionally implement 'APN override' mechanism to get around the headache of communicating the settings to their subscribers every so often as well as to reduce connection hitches due to misconfigured APNs.

PS : For Airtel OpCos, the new Airtel Modems come with the settings of all Airtel Operations across Africa pre-configured on the dashboard; you can check there too.