Primary NETWORK not available

Hi all,

I have an iPhone XS that was locked to EE I’ve spoken with EE several times now and they confirm my iPhone is fully unlocked, however, I can’t use any sims as when I do I get “call failed “ all the time. When I investigate and go into setting ,general,about, scroll down to primary then NETWORK- not available. However, the phone does recognise the CARRIER : giff gaff any help please thank you