Need to sim unlock my old work iphone7

[Contactjon]

I retired in July 2000 and my employer let me keep my iPhone 7 that was sim locked to the o2 network. I need to use the phone on another network until another damaged iPhone can be repaired. The sim was deactivated when I left my employer, how do I unlock the phone so that I can use with another network? I have searched help & support pages and discussion threads but cannot find anything there to cover this particular issue.

[madasaf1sh]

@Contactjon 

You will need to contact your previous employer, and ask them to reach out to the network they used, there is nothing o2 can do to unlock it. 

Or go to a local phone shop and see if they can unlock it.

[Enlli]

This may help

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

[jonsie]

You will need to put in a O2 sim and use it on the network to make a few calls and send a few texts

Then follow this guide

Guide: Cancelling Your Contract 

It has to  be used again on O2 so that the IMEI number will be recognised as being used on the network