What is an APN?
An APN, or Access Point Name, is used to connect your device to the mobile network. You need an APN to use mobile data and send MMS when you're not connected to Wi-Fi. These settings are usually added automatically, but in some cases you may need to configure them manually.
How to Set Up APN Settings on iPhone and iPad
Go to Settings.
Select Cellular, then Cellular Data Network.
Enter the following information in the corresponding fields (leave all other fields blank):
Cellular Data
APN: online.telia.seMMS
APN: mms.telia.se
MMSC: http://mmss/
MMS Proxy: 193.209.134.132:80
MMS Max Message Size: 2097152
Restart your device.
Done! Your APN settings have been configured.