Radio

The Shortwave Radio or Service Radio is the primary means of communication between the player and other characters. Because shortwave radios operate within a small band of frequencies, the signal is easily disrupted.

BioShock
At the beginning of Welcome to Rapture, Jack is asked (by Atlas) to pick up the shortwave service radio in the Bathysphere. The radio is carried throughout the whole game and is automatically activated by an incoming transmission. The service radio is set for a specific frequency which is disrupted by Sander Cohen during Jacks exploration of Fort Frolic. Cohen most likely changed Rapture Radio's station frequency to match that of Jack's shortwave. Rise, Rapture, Rise can be heard playing at the beginning of the frequency disruption.

BioShock 2
The radio will be making a return appearance in BioShock 2. It appears to be covered with a thin layer of seaweed, slime, and coral.

Trivia

 * In the first BioShock, the antenna on the radio in the bathysphere and on the HUD icon are reversed.