The phone is constantly on 'offline mode' and does not recognise any sim cards

Offline mode means that your phone aint getting any signal from your mobile service provider's BTS. You need to check it from your mobile service provider if there's an ongoing outage, you need to check as well if the sim card is properly inserted. Try powercycling your phone.
1. Turn off your device.
2. Remove the sim, memory card and battery.
3. Wait for at least 2minutes.
4. Plug back the SIM card, memory card and battery.
5. Turn on mobile phone.
6. Check if you are still getting offline mode.
7. If so, try to insert your SIM card to a different phone.
8. If using a different phone for your SIM displays offline mode still,then its your SIM card which is faulty. If it works fine make sure that you inserted the sim properly or the SIM card slot might be faulty.

try these steps..
1. get another sim card insert it to your phone (this will help you troubleshoot the problem between phone and sim).
2. check the phone profile settings, if it's on offline mode, then select general, or silent , it's up to you but don't choose offline mode.
3. clean the contact surface of the sim card by pencil eraser and a piece of clean soft cloth.
4. reinsert and try.

actually there is a problem with either ur sim card or ur phones sim card slot
1. Try putting some other sim card and donot use ur phone in offline mode .
2.If u still have the same problem then there is a hardware problem go to nokia

It is that's why because your phone is get locked unlocked it and then you can use any of sim you want too. :)

when you insert sim in your phone after using it offline,it should ask you if you want to continue using your phone in offline mode...select NO..Otherwise your phone cannot detect the sim card..clean sim terminals..if problem persists check and reheat sim filter IC..the crystal one, near the sim terminals itself..if all fails then UPP (CPU) or software problem..

The phone is showing Offline, hence I have inserted the sim card and switched the phone on, and choose general profile too. But it is showing Please Insert Sim Card. Please help with a solution.

'whether you want to continue in offline mode y/n'.,

when it displays this messege

press no

and u r done

It would appear that the problem lie with the SIM card - my phone could no longer read the SIM and therefore only the offline mode was available. I tried my SIM in a different phone and it couldn't be read either. I replaced my SIM with a pay-as-you-go SIM and the phone was working perfectly well again.

I will be speaking to O2 to identify the problem with my SIM.

The problem is with the sim card. try to remove the sim, clean it with a dry cloth and put it back in. if the problem is not solved, take back the sim to your network provider and get a replacement, asuming the sim is damaged

take the sim card and put it bck again.restart it...there it will say "CONTINUE IN OFFLINE MODE?"....select no there...choose another profile and press ok...offline mode will b disabled....