Default No Network Suddenly Please Help

Hi guys, I got a problem I need you guy to help me with my HTC again. Suddenly I lost network signal on my mobile, I have rebooted the phone. removed and inserted the sim no results.

I went further to hard reset, factory and even flash custom rom and back to stock still no network. Yes I have tried this simcard on my iphone and it works.

I have tried 3 other network simcards on my HTC and none of them works. Can anyone advice on what I can next? Am confused, every other thing works except no network.

HTC one (M7)
ROM: Stock, 4.4.2 Kitkat.

History: HTC One X, iPhone 4, iPhone 3G, Blackberry Bold 2, Blackberry Curve 3G, Nokia N95 8GB(Still in love with it), LG KU990 Viewty, Sony Ericsson K950, Motorola Razor, Motorola v3 ,Nokia 3310