Modem (Modulator/Demodulator Unit) 2 : A device that converts data that is compatible with data-processing equipment to a form that is compatible with transmission equipment, and vice versa
NFPA 1221 Standard for the Installation, Maintenance, and Use of Emergency Services Communications Systems, 2007 ed. (Std: Install, Maint, and Use of Emr Srvc Commun - Amer) {391 NFC}