Phone a friend is an area/option in Fleeing the Complex.
The area is reached when Henry first chooses to "wait for transfer" on the start screen, and, once he is in his cell, uses the laser plane to break out. He ends up in the office underneath his cell, crushing a guard in the process. There, he finds a cell phone and can proceed to call one of 2 people for help: the Toppat Clan, or the Government (more specifically, Charles).
Both choices are call backs to the previous game, Infiltrating the Airship. That game had multiple, radically different endings. Which friend the player decides to call automatically determines which ending from "Airship" is continued from. When Calling the Toppat Clan, the game continues from the Rapidly Promoted Executive ending with Henry still being the new Toppat Leader, this leads to The Betrayed ending. When calling the Government, the game continues from the Government Supported Private Investigator ending, with Henry and Charles still being on good terms with each other and Charles recalling how he and Henry worked together like this before, this leads to the International Rescue Operative ending.