Modat, also written MODAT, is an obsolete Motorola data system using a sequence of seven audio tones similar to the five-tone-sequential Selcall format. Some systems still use Modat today. Modat is used for unit ID and emergency buttons, rather than for selective calling. In a typical installation, each radio in a system is assigned a unique seven-tone code. Each time the radio's push-to-talk button is pressed, the radio transmits the seven tone sequence at the beginning of the transmission. To prevent the user from talking while the tone sequence is broadcast, the seven-tone sequence is played over the two-way radio receiver's speaker.