Chosen Solution
So basically I have bought a new gold housing of eBay for £15, it fits great and looks great. I put the motherboard in and put the screen on , but it only picks up 1 or 2 bars connection to my sim card, and it says failed to make call. The motherboard is not faulty at all, So I put all the parts back into my original housing and it instantly picks up full bars and makes a phone call straight away with no issues, The housing I bought of eBay is not genuine it is suppose to be a very good 3rd party part , As I said it looks it and feels it but I don’t think the connection is getting through the cheap material, Where can I buy a good housing what will not interfere with the connection?
Third party parts are always a gambl, and I think you might have fallen into a 3rd party trap. I would buy a used OEM part from here at iFixit instead. If the SIM is still not recognized after you try out this housing you can return the housing quick and easy. iPhone 6 OEM Rear Case
