Sim not working in new phone

[Erleemo]

Hi I sold my unopened upgraded iphone 11 pro max, the buyer has contacted me saying when he inserts his o2 sim it’s not recognised? But when he inserts a family members Vodafone sim the phone works fine. It’s the same o2 sim he’s using in his current phone iPhone X. He is saying it’s locked to Vodafone? any advice please thank you

[Cleoriff]

@Erleemo 

That's not true. O2 have been selling all phones unlocked since June 2018.

It used to be that iPhones locked to the first sim inserted (if bought from CPW) but I'm not aware that's still the case.

As your post indicates the first sim he inserted was O2, so if any locking took place it would be to that sim. It could be a problem with his sim. He should remove it, clean it gently and reinsert it properly (which is upside down) reboot the phone and see if that works.

If not, I suppose as the seller, it's will be your job to sort this out

You need to contact O2. All numbers are in this guide. Guide: Coronavirus Community Help and Support 

[Erleemo]

Thank you for your reply. I’ve contacted o2 twice via live chat it was suggested to unlock the phone to all networks but like you say I thought it would already be unlocked? Seller also says he had to unlock his iPhone X as that wasn’t unlocked to all networks which he got from o2?. Maybe he inserted a Vodafone sim first that could be the problem I wasn’t aware of that! Thank you again

[Cleoriff]

@Erleemo 

Although I don't think it should be locked, here's a guide

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

[Erleemo]

Thank you I’m thinking he put the Vodafone sim in first that’s why we have this problem. If it’s now locked to Vodafone will o2 still be able to unlock it to all networks? I’ve tried unlocking it via live chat yesterday but there system was down I’ve also tried doing it online but it’s not happening.

[Erleemo]

I’ve used your link, the request has gone through and I will be contacted within 7 days. fingers crossed it’s sorted! Thanks again for your help

[Cleoriff]

It's an unusual situation @Erleemo 

1) The phone was bought from O2 and therefore should not be locked.

2) He put an O2 sim in and didn't work

3) Worked with a vodafone sim.

So that leads me to believe it's a problem with his O2 sim. He may need to get a new one.

I suspect your O2 unlock request will come back with the message 'unable to unlock' (which usually means it's already unlocked)