- Setup a default mobile data internet access point, go to Settings > access point, and select your network operator or enter a new (+) APN settings related to internet and/or MMS as needed. Confirm the selection by pressing Done key at the bottom of the screen. (Note: You can only edit APN settings which have been manually configured).
- Confirm with your network operator that you have an active mobile data subscription (access to internet) on your SIM card.
- Enable the cellular data connection on your phone, go to Settings > cellular and switch Data connection to On.
- Check that your data roaming is activated when you are not in your home network, go to Settings > cellular and select data roaming options.
- If the data connection is lost, try reconnecting by switching Flight mode on and back off: Tap Settings > Flight mode. This resets the active data connection.
The previous actions usually solve your problem. If it does not help, insert your SIM card in another device and retry. If it is working in another device, contact your network operator for Internet settings reconfiguration or you may need reset the phone to factory settings (Settings > about > reset your phone).