i phone 4 black 16gb factory unlocked , ?

hi i have i phone 4 black its like brand new even have front and back original screen protector butt because of some reason its not making calls. some 1 told me its will work in any other country , actually i buy from eBay and i cant return. its have apple manufacture warranty till 2013 black 16 gb no scratch no box and accessories . 7j110t9ua45