Bought refurbished iphone on PAYG - "SIM not supported" message

[Jimony_Griffman]

Hi all, so I currently have a PAYG sim on my previous old iphone and bought a refurbished iPhone XR directly from o2. They sent a PAYG sim with the phone, though I plan to use my previous Sim card/number. When I try to set up the phone I get a message saying

"SIM not supported

The sim card you currently have installed in this iphone is from a network provider that is not supported under the activation policy currently assigned by the activation server. This is not a hardware issue with the iphone.

Please insert another sim card from a supported network provider or request this phone be unlocked by your network provider. Please contact apple for more information."

[MI5 · Accepted solution]

@Jimony_Griffman 

It means the phone is locked to another network.

If O2 supplied this phone to you they either need to arrange to unlock with the other network or send you a replacement phone.

[Jimony_Griffman]

Thanks very much for the quick reply. Is there an obvious quick route to getting this arranged? I bought this on the website and usually end up going round in circles when trying to contact these big companies.

[MI5]

@Jimony_Griffman 

If you message O2 on Facebook (https://o2uk.co/O2CFB) , Twitter (https://o2uk.co/O2CTW) or Instagram (https://o2uk.co/O2CIG) , they should be able to help you with this.
Thanks.