i have unlocked phone wont go online, recieve mms, and sends text to wrong person

Ok i got this unlocked phone from ebay its sort of weird it is compatable with T-Mobile and att! The IMEI number comes back unknown manufacturer. when i send a message to a friend it goes to someone else in the phone book. it is internet compatable but says there is a conection problem so i re programed it and am still having issues i think the number it diales is wrong. Can someone please help me i cant afford a new phone and would really like to get this one working almost right !