Was your SIM/service ever working correctly?
Is your phone unlocked for use on any network?
Are there any error message displayed on your phone?
Does your phone have a connection to the 48 network?
If not then if you do a manual search for networks can you see and connect to 48?
Do you have an active membership plan?
Did you configure your APN settings for mobile data by texting "APN" to 50048 and following the instructions?
If you need to contact 48 support about this then see the links in my signature below.
