charge for a telephone call
no-charge call (e.g. via Skype, etc.); toll-free call
(telephone) speech quality; sound quality; call quality
intra-city telephone call; local call
call-waiting (phone option)
intercom; intercommunication system
person-to-person call; personal call
conference call (phone option); conference calling
station-to-station (comms)
silent time; silence period
intercom; intercommunication system
phonetic alphabet (e.g. A for alpha, B for bravo, etc.); phonetic code