The Term "jailbreaking" In iphone Terminology Refers To The Altering Of The Phone's Firmware To Allow Third-party Applications And Custom Editing. Meaning, It Gives You Full functionality Over Your iphone And Allows You To Do Things That Apple Does Not Technically Allow. If You Have Attempted To jailbreak Your iphone 3g, Or If You Have Purchased A Used iphone 3g And Wonder If It May Already Be Jailbroken, Just Look For The telltale Signs To Know For Sure.