iPhone 7 can't find network

My iPhone won't connect to my mobile network, it says "searching" constantly and when you go to the settings the mobile data section is blank / greyed out on the control centre. I've tried resenting the network settings, inserting a sim on a different network putting my sim into another phone (which works).

My last resort was to reset my phone completely, which now has added to the issues where my phone is saying it's unable to activate because the server is temporarily unavailable. I've tried connecting my phone to itunes to activate it but it still won't activate.