This type of monitoring is most commonly used in home alarms or premises that do not require an insurance rating, i.e. homes, small offices, etc.
The dialer is attached to an existing phone line and when an alarm occurs, it seizes the line and dials the central station, the central station receives the number transmitted and a data base is triggered to give the address, type of alarm, and instructions of who to call or dispatch, example: premises, fire, police, ambulance, etc.
This type of communication can be defeated by cutting the telephone line, and can be backed up by a cellular link, which is an additional cost.
DVACS (Digital Voice Access Control Systems)
This monitoring involves a leased line from Bell Canada and is dedicated to security systems. It is supervised so that if it is cut an alarm will occur.
This is used mainly to monitor fire alarm, sprinkler systems, jewelry stores, banks etc.
Because of the leased line costs from Bell Canada, the monthly charge for this service is much higher than for digital dialers.