When was it working ok for you last?
What changed in the meantime?
Do you have a connection to the 48 network - i.e. signal bars?
If not then if you do a manual search for networks can you see and connect to 48?
If you do have a network connection then can you receive calls, send/receive texts and use mobile data?
Do you have an active membership plan?
Does the problem arise with all contacts?
And even if you dial a number manually?
Have you tried switching off your phone and reseating your SIM just in case it's somehow dislodged?
Can you try your SIM in another unlocked phone?
If you need to contact 48 support about this then see the links in my signature below.
