When was it working ok last?
Can you send a text, use mobile data, receive calls and texts?
Did anything change on the phone recently?
E.g. software update, settings changes, factory reset/restore, new phone handset, returned from roaming abroad, etc.?
Maybe try reseating the SIM just in case it became dislodged?
Maybe the SIM has developed a fault and you'll need to try a replacement?
Can you try it in another unlocked phone first just to see what happens?
If you need to contact 48 support about this then see the links in my signature below.
