I can confirm the phone i have purchased second hand off eBay is indeed blacklisted/reported stolen you must watch out for these issues when buying on eBay, id advise Muhanad you ring up your service provider and ask them to check the IMEI dial *#06# on your keypad write it down and ring them also go onto http://www.imeipro.info/this will also indicate if your phone is blacklisted.
Orange & O2 & EE:
If you place an active orange or O2 SIM into a blacklisted handset you phone will not show any signal strength at all!
Vodafone & T-Mobile
If you place an active Vodafone or T-Mobile SIM into a blacklisted handset, the phone will appear to function perfectly UNTIL you try to make an outgoing call. When you try to call out from the handset the call will be dropped!!
hope this is useful.
Jamil