The two districts are east of the Dan Ryan Expressway, between about 31st to 75th streets.
The robbers order the food using cell phones, the community alert from Calumet Area detectives said. When the drivers arrive at the location the food was ordered to, they are then robbed at gunpoint, the alert said.
Pizza delivery driver Johnny McCurine saidhe takes precautions on every run.
"I try to make sure I don't bring a lot of cash out with me," McCurine said. "And I don't go in unfamiliar areas at all."
The cell phone numbers that have frequently been used in these robberies, according to the alert, are: (773) 712-3426, (773) 757-4971, (773) 587-7674, (773) 683-8649, (773) 765-8423, (773) 936-0533.
At Miller Pizza Company on 35th Street, that list of numbers now sits by the phone.
"It is a concern, but we remain vigilant and cautious about every order that we take over the telephone," said owner Rod Miller.
Police advise business owners in these areas to only allow delivery orders to be placed from business or residential land lines only, not from cell phones. They also say that upon arrival at delivery locations, all drivers should call the customer prior to exiting their vehicle, and make visual contact with the customer prior to exiting the vehicle.
Additionally, police say, business owners should be suspicious of large orders where the customers request change for large denominations.
Police ask that 911 or Calumet area detectives be notified immediately with suspicious numbers, and that businesses keep a log of frequently used suspicious numbers.
If anyone has information concerning these incidents, they should call Calumet Area detectives, at (312) 747-8273, or send tips to firstname.lastname@example.org.