unlock and old iPhone

[DG2022]

Hi, I have an old iPhone which had an o2 sim card. I bought a new contract and number with o2 so the phone became dormant. I want to unlock the old phone and put a vodaphone sim card in......could I ask how do i do this?

[Bambino · Accepted solution]

@DG2022 See this: Unlocking an O2 phone to use a different SIM card. - o2uk