No service on iPhone 5s
I bought a used iPhone 5s and it was meant to be unlocked. I put in my 3 network SIM card and it says 'sim not supported' and it does not let me use the phone. When I put in my O2 network SIM card it lets me use the phone, starts searching however it says 'no service' in the top left of the screen. What I tried:
1. I tested both SIM cards in a different phone and they worked.
2. Resetting network settings.
3. Rebooting the phone.
I did a lot a research on forums but can't find an answer. The phone gets very good WIFI signal so I don't think it's an antenna. And when I put in that 3 network sim it says 'sim not supported' however it shows three circles in the top left corner so I'm not sure if that means 3 bars of signal. The IMEI is: 352054062049680
Is this a good question?