Trick
How to use airtel 20GB for 200naira on psiphon vpn
You have to leave your apn settings in default;
APN settings
Name: anything
Apn: internet.ng.zain.com
Apn type: default,supl
Proxy: Not set
Port: Not set
Username and password: internet
So after activating the offer, you will have to use it on psiphon kindly click here and download Psiphon vpn then after download, launch or open it then configure it like this below.
Tick Remove Port
Proxy Type: Real Host
Proxy server: nokia-s40-11-cust.opera-mini.net
Real Proxy Type: HTTP
Real proxy port: 80 or 8080.
Then after this, kindly go to OPTIONS then choose UNITED STATE as your country region after that, kindly click on MORE OPTIONS and untick CONNECT THROUGH HTTP PROXY