In the United States Navy, “IC” stands for Interior Communications.
An IC is a rating that operates and performs maintenance on:
Alarm, warning, and indicator systems
Interior communications
Ship’s control, entertainment, and navigation systems
An IC’s day-to-day duties include:
Maintaining or repairing interior communications systems
Maintaining and repairing shipboard navigation equipment
Testing and repairing interior communications
Installing phone and other comm circuits, boxes, and switchboards
Maintaining dead reckoning and course-plotting equipment
An IC must have:
Above average math skills
Good dexterity
Great speaking skills
An interest in technology and information
Enlistees are taught the fundamentals of this rating through on-the-job training or formal Navy schooling.