No service on iPhone 4 but still have 3G?

Just today the signal on my iPhone 4 suddenly disappeared and now says no service I can't make a call or receive neither can I with texts but I still have access to 3G and the Internet on my 3G works perfectly fine I checked the status of my network and it says my area should be making and receiving calls and texts fine my phone is brand new just about 3 week old

Added (1). Stupidly I forgot to list what I've already tried, I've tried resetting the settings, updating the phone, resetting through iTunes, hard resetting phone and turning off for a period of time nothing has fixed the issue if my Internet was affected too I'd take for granted that the phone had already broken its annoying since I've had the phone such a short time

You can try to reset the network settings. (Settings… General… Reset… Rese… Network settings) this will not cause you to lose any info. If that doesn't work connect it to itunes for a backup n restore.