Open the Settings app in Firefox OS.
Go to Cellular & Data, Turn on Data Connection.
Scroll down and tap Data Settings button and get the screen to enter the APN Settings.
APN: telia
Identifier:
Password:
Press OK.
Go to Cellular & Data 
Message Settings
APN: telia
Identifier:
Password:
MMS Proxy: 212.169.66.4
MMS Port: 8080
MMSC: http://mm/
Press OK.
