Pause the game and go to your cell phone. Select "Dial" and enter any of the following Service numbers. Then select "Call":

SERVICE - NUMBER
Airport - 5553597
Big Willy's Cab - 8198415
Bling Bling - 5554233
Brown Baggers - 5553765
Cocks - 5552626
Company of Gyros - 5554976
Cycles - 5552453
EagleLine Yellow - 0180174
Emergency - 911
Eye for an Eye - 5555966
Foreign Power - 5552046
Forgive and Forget - 5554448
Freckle Bitch's - 5556328
Friendly Fire - 5554867
Fire Department - 5553473
Giftshop - 5557577
HazMat - 5556677
Image as Designed - 5558459
Impression - 5553248
Leather and Lace - 5552662
Legal Lee's - 5559467
On The Rag - 5555926
On Thin Ice - 5552564
Police - 5557973
Pimps 'R Us - 5557467
Rim Jobs - 5553493
Rusty's Needle - 5558287
Ship It - 5557447
Spelunkers - 5552283
Suicide Hotline - 4876837
Tee'N'Ay - 5559866
TNA Taxis - 4558008
Ultor Security - 411