Unlatching - O2 say not their number

[lilian54]

My partner wants to use my old Samsung Galaxy S3 until he gets a new phone. The screen shows the O2 logo when it starts up, but O2 say the number isn't theirs and they can't unlatch it.  I can't remember which provider i had it with. He's tried a Three SIM, but it says 'no SIM' which I assume means it's locked. Would be grateful for advice.

[Cleoriff]

@lilian54 

If you can't remember which provider you were with, your best bet is to find a mobile repair shop, or market stall trader who will unlock it for you.

[jonsie]

You need to have an O2 sim card in the phone to get it unlocked @lilian54 

Guide: Cancelling Your Contract 

[MI5 · Accepted solution]

@lilian54 

It will be locked to O2 if it has O2 firmware on it.

You'll need a current O2 sim to unlock it, either a contract sim borrowed or get a PAYG sim to use in it for a few days.

All you need to know is here Guide: Unlocking an O2 phone to use a different SIM card 

[jonsie]

oops...wrong link

[lilian54]

Thanks everyone for your advice, much appreciated.

[jonsie]

You're welcome

[MI5]

You're welcome @lilian54