Unlocking old contract phone

[Anonymous]

Hello,

I am looking to unlock an old contract phone with o2 (HTC One) which was out of contract six months ago which was subsequently upgraded through o2 to a HTC One m9, maintaining the same phone number. I have went through the online form only to be bounced back with the inability to unlock the phone. I wish to give this phone to a relative and I need to phone unlocked for this, any suggestions would be much appreciated! 

[Bambino]

@Anonymous I believe you would have to put your sim back into your old phone to re-register it on the network before you can unlock it. Are you certain the phone is locked? Have you tried to use it wth another sim card?

[MI5 · Accepted solution]

Just put your sim back into the old phone and use it until the phone shows in your MyO2 http://www.o2.co.uk/myo2 Once it shows in there you can click the link to unlock it from your MyO2.