Apple iphone 4 32 GB not signal coming -

hi I bought this phone from gumtree three month ago it was working fine and work with 02 network but now its still working but i cant call anyone but mobile sim internat still working i spend 350 for this phone anyway ......give me a good offer email me and keep ur phone number and i will call u back thanks BNIB 32GB White APPLE iPhone 4 S Brand New Fully Boxed with Apple Accessories. Complete with Store Receipt. 12 Months Apple Manufactures Warranty. iOS 5 Software and 32GB built in Memory. Factory Unlocked for all Networks. Also comes with Free White Bumper Case. If you leave a contact number i can call or text you if easier. CASH COLLECTION OR PAYPAL & POSTAGE CAN BE ARRANGED Thanks I am selling my Blackberry 9790 which is the latest Blackberry Bold in the market. This phone has all the features of the Bold 9900 but in a more compact and sleek body. The phone is in excellent condition and is fully boxed with all original accessories. I am open to sensible offers and swap. you can text me on 07900 170000. samsung galaxy s3 in white unlocked any network boxed as new also has leather case may p/x another phone i will not do a straight swap so please dont ask NEW GALAXY S3 PEBBLE BLUE 32GB UNLOCKED TO ALL NETWORKS FOR SALE. COMES WITH BOX AND ALL ACCESSORIES. BOX HAS BEEN OPENED TO CHECK CONTENTS AND THE PHONE IS IN WORKING ORDER. CASH ON COLLECTION 520. O.N.O NO TIME WASTERS PLEASE. CONTACT 07858511843