Iphone 4 - No service for non UK Sims

Hi

My old iphone 4 was locked to Orange. After calling EE who unlocked the phone for me, it only seems to work for UK sims (I have tried Virgin and Orange sims which work fine)

However it says "No Service" in the top left corner of my screen for other EU sims (namely Cyprus sims)

Any help would be appreciated. I have already tried to reset network settings but no luck and have contacted EE but they could not help me.

Thank you