Sim not supported on Iphone 6

[sebk]

Hello, 

I've updated carrier settings on Iphone 6 (unlocked) and after inserting the sim card, now I've got message sim not supported. The same sim card works fine on my Iphone 8. Has anyone knows how to resolve it ? I've tried already resetting the network settings and restoring the phone to the factory settings but nothing works. I've tested using sim cards from other operators and didn't have any problems. 

Thank you for any advice

[pgn]

When your iPhone says SIM is not supported, it usually means that your (second-hand?) iPhone is locked to a carrier.

You can go to Settings > General > About > Find Carrier Lock and check if it shows No SIM restrictions, then your iPhone is unlocked

Odd that you know it is unlocked but the SIM throws that message... was it a SIM from an old Contract phone that has been ported to another network, rather than a (recent, within 6 months!) PAYG SIM, @sebk?

[MI5]

@sebk 

Have you tried connecting phone to iTunes?

[sebk]

Hi @pgn  thank you for your reply. The setting you've mentioned is not there as the phone has installed iOS is 12.5.7 and can't be updated any more. The only info related to network is Carrier O2 36.2. The sim is around 12 months old from O2. Phone is definitely unlocked as it works fine with vodafone and three sims so I am a bit puzzled.  

[sebk]

Hi @MI5 , nope as I use only iCloud backup. I will give it a go to see if that helps. Thanks for the suggestion.