Unlock my old iphone but I no longer an o2 customer

[jasewood65]

How do I unlock an old iphone (registered in my name still) but I no longer have an o2 account. I can’t send the form off as it’s asking me for my account number. 

[Bambino · Accepted solution]

@jasewood65 See this guide: Unlocking an O2 phone to use a different SIM card. - o2uk