Cheat List
Unverified. You must pause the game and hold down the L or the R TRIGGER. This will access the phone. Select DIAL, then enter and CALL:

Ambulace (Restores Health) 911
Brown Baggers 555-3765
Eagleline Yellow (Taxi Service)(555) 018-0174
Eye for an Eye Voodoo 555-5966
Give money #66639
God's Wrath (lightning strikes randomly) #10
Police level reduced #nocops
Gang level reduced #no gangs
Grounds for Divorce 555-9473
Infinite Ammo #AMMO
Infinite Sprint #SPRINT
Legal Lee's 555-9467
Lik-a-Chick 555-3863
On the Fence (Pawn Shop) 555-7296
On The Rag Clothing 555-5926
Rim Jobs 555-3493
Stocks 555-2626
Suicide Hotline 1-555-ITS-OVER
The Dead Cow 555-6238
TNA Taxi Service 555-455-8008
GameStop T-Shirt #42637867

#Rocket ... Activates RPG cheat
#AS12Riot ... Activates Riotgun cheat
#Krukov ... Activates Krukov cheat
#12Gauge ... Activates 12gauge cheat
#Tombstone ... Activates Tombstone cheat
#T3KUrban ... Activates Urban cheat
#GDHC50 ... Activates GDHC 50 cheat
#Shepherd ... Activates .44 Shepherd cheat
#NR4 ... Activates NR4 cheat
#Pipebomb ... Activates Pipe Bomb cheat
#Vice9 ... Activates Vice9 cheat
#Knife ... Activates Knife cheat
#Molotov ... Activates Molotov Cocktail cheat
#Grenade ... Activates Hand Grenades cheat
911 ... Slow life regeneration (?)
#42637867 ... Gamestop/EBGames t-shirt (costume)
555 018 0174 ... Access Eagleline Yellow (Taxi Service)
555 455 8008 ... Access TNA Taxi Service
555 5966 ... Access Eye for an Eye Voodoo
555 7296 ... Access On the Fence (Pawn Shop)
555 3863 ... Access Lik-a-Chick
555 6238 ... Access The Dead Cow
555 3493 ... Access Rim Jobs
555 9467 ... Access Legal Lee's
555 9473 ... Access Grounds for Divorce
555 5926 ... Access On The Rag Clothing
#SPRINT ... Activates Infinite Sprint
#66639 ... Activates money accruement
#AQUA ... Activates and spawns an Aqua car
#AMMO ... Activates infinite ammo
#10 ... Activates random lightning strikes
555 3765 ... Access Brown Baggers
1 555 ITS OVER ... Access Suicide Hotline
555 2626 ... Access Stocks
555 2445 ... Guy in chicken suit (?)

Note that the in-game cheats (i.e., Pipe Bomb cheat) must be toggled on the in-game cheat menu. Toggling cheats on will remove the possibility of earning gamertag achievements. Simply toggle off cheats and reboot the game to continue earning achievements.