IPHONE 4 16GB BLACK - ALMOST NEW CONDITION - NO SIGNAL !

hi, this is my ad for my iphone 4 16gb in black in immaculate condition, which was brought a month or 2 ago from the ad mag and was running well until i stopped receiving signal, so i rang back the person who had sold me the phone and they said it was working when sold.. i am using this phone with wifi to watch movies and browse the internet just any calls or texts cant be made! everything else works fine, comes with phone and headphones as the charger my brother is using. 180 o.n.o please text me or call on 07722913033 no timewasters please