APN (Access Point Names) means a network or carrier that your cell phone or tablet accesses for data. It describes which wireless network you are using when you try to connect a telecom operator such as AT&T, Verizon, T-Mobile etc. It also defines your IP address type or security mechanism.
You may need to change your sim card’s APN for several reasons (Especially for testing purposes). The way to change APN depends on your device:
- iPhone: Settings > General > Network > Cellular Data Network
- iPad: Settings > Cellular Data > APN Settings
- Android: Go to Settings > Wireless & Network > Mobile Networks > Access Point Names
- PC: Use your carrier special application. For example, It is AirCard Watcher If you are using Sierra Wireless Data Card. You can change it when internet is disconnected. After changing it, you must unplug and plug it in again (It is called Power Cycle). Don’t forget to change “Connection type“. It must be “Autoconnect“.