Entering Cheats
While previous entries in the "Grand Theft Auto" series had you press seemingly random button combinations to enter cheats, "GTA IV" and "The Ballad of Gay Tony" use phone numbers as cheats. While you're playing, press "Up" on the D-pad to open Luis' cell phone. Pressing "Up" again grants you access to the phone's keypad, where you can enter cheats. After entering a cheat, you'll find an option to toggle the cheat on and off under "Options" in the cell phone.
The Parachute Cheat
Enter the phone number "359-555-7272" into Luis' cell phone to spawn the parachute. Gaming website Cheat Code Central warns against saving games with cheat codes enabled, saying it may cause in-game problems.
Unlocking the Parachute
You can still enjoy the game's fun base jumping without using the cheat. Early in the game's main story, you unlock the ability to participate in base jumps. Once this is unlocked, pink parachute markings on your map signify an area with a base jumping challenge. The challenges take on one of three forms. "Target Jumps" have you jump from a building and try to land in a specific spot on the ground. "Vehicle Jumps" are similar, except you're trying to land on a moving vehicle. With "Heli Jumps," you jump from a helicopter and glide through rings that guide you down to a ground target similar to those in "Target Jumps." After completing all 15 base jumps, Luis' apartment gains a parachute you can go get at any time without using the cheat.
Controlling the Parachute
After jumping from a building, you first control Luis' free falling. Press the button you use to walk forward to speed him up and dive or the button you use to walk backward to slow down his descent. Left and right turn him as they do when walking. Press the "Run"/"Handbrake" button to activate the parachute. Controlling Luis with the parachute deployed is similar to the free falling controls; "Forward" makes Luis glide farther, "Back" makes him descend quicker, while "Left" and "Right" change his direction.