What's the apn settings?
The term APN (Access Point Names) refers to one specific setting but also the collection of network gateway settings your mobile broadband device uses to reach the Internet.
Many SIM cards store the APN data that gets configured on your mobile broadband device automatically when the card is installed so Your device should be ready to go online as soon as you turn it on for the first time. However, if you can’t go online, it’s usually because the Access Point Name (APN) settings on your device (which dictate what your device will try to connect to) are different from those on your SIM (which dictate what your device and SIM are allowed to connect to). In that case you will need to configure APN settings manually
How to configure APN Settings on EE osprey and Alcatel modems that have a web management interface ?