Unlatching an old phone

[ParkyRam]

Not sure where to post this, but I'm trying to unlatch an old phone of mine for my mum to use with a sim from another network. I've sumbitted the IMEI number via the form on the 02 website, but it is telling me that the phone isn't an 02 device. I know it is, as I have been with 02 for over 15 years. The device is an S6, so probably around 6 years old? 

Any ideas how else I can unlatch the phone?

Thanks in advance 🙂

[MI5]

@ParkyRam 

How to unlock here but check with another sim too first 

Guide: Unlocking an O2 phone to use a different SIM card 

[MI5]

@ParkyRam 

If you bought it from Carphone warehouse it won't be locked.

[ParkyRam · Accepted solution]

Thank you for the reply. I didn't buy from Carphone Warehouse, it came direct from 02 online, but it wasn't locked anyway.

Much appreciated.

[MI5]

O2 haven't locked any phones since early 2018 but some before that weren't locked either.