Contact ID is a specialized communications format that uses what type of signal?

Contact ID is a specialized communications format primarily used in alarm systems to transmit event notifications. This format utilizes a series of tones to convey specific information, such as the type of alarm event and the status of the system. The tone signaling is designed to be easily interpreted by receiving equipment, allowing for quick and efficient recognition of incidents.

Using tones enables consistent transmission of data over a communication channel, ensuring that the information sent from the alarm system can be reliably decoded by monitoring stations. This method is advantageous in situations where clarity and accuracy are essential, as each tone can represent a different type of event or status, reducing the likelihood of misinterpretation or confusion. This makes it an effective choice for alarm and intrusion detection systems.