Possible Clues:

• Syst. with hand gestures
• It's used at Gallaudet U.
• Comm. system in the film "CODA"
• Communication sys. at Gallaudet
• Digital communication, for short?
• Subj. at a school for the deaf
• Handy communication syst.?
• "The Joy of Signing" subj
• Digital communication?: Abbr.
• Manual alphabet, briefly