Check IMEI to Confirm phone is unlocked

bignred05

Can anyone please point me in the right direction 

I have sold a phone as unlocked to Music Magpie.

the phone was originally bought from the BT shop, I still have the invoice & box clearly marked as EE - Unlocked.

I have used several different network sims in the phone (Samsung A90 5G) including EE & 3.

I have sold the phone to Music Magpie, who are telling me the phone is locked to O2/Giff Gaff.
* not sure where they get this from as originally they said O2, now I have queried this they mention Giff Gaff. 

And as such have revised their offer, 

I never use/buy locked phones which is another point.

Prior to sending the phone off I took a number of photos to show the phone as working and no damage (scratches etc) I wish I took one of the network/imei details to show it as unlocked now.

is there a reputable way to check the IMEI number 
Any help/advice would be appreciated 
thanks 

chistery

reject the offer and check it when they return it?

bignred05

chistery said:

reject the offer and check it when they return it?

I am in communication with MM on this matter and have sent them 
the original invoice stating (EE - Unlocked) along with photos of the box showing the IMEI number and the order details again stating EE - Unlocked.

I just wasn’t sure if there was a way to check the Imei number to show it is unlocked.

bignred05

How utterly bizarre Music Magpie are still insisting the phone is locked to O2

despite providing the original sales invoice along with original box details both stating EE - Unlocked 

offer declined 

lesson learnt, next time take photos of imei/network status along with different sim in phone