To get a jet pack in Grand Theft Auto 4 for the PlayStation 3 console, go to the safe house, and dial the number 359-555-0172 into Niko's cell phone. The jet pack should appear outside the safe house.
There are a variety of cheats available in the game by dialing specific numbers into the character Niko's cell phone. To change the weather, dial 468-555-0100. To get an increased selection of weapons, dial 486-555-0100. To raise Niko's wanted level, dial 267-555-0150. To lower Niko's wanted level, dial 267-555-0100. To restore health, armor and ammunition, dial 482-555-0100. To get information about the song playing, dial 948-555-0100.