The alarm system has an alarm unit for ready access at a point of entryway which communicates with a line seize module located in a secure location. The alarm unit has a transmitter receiver, a control panel function, a key pad, and an input/output port for connection to telephone wiring for communicating with the line seize unit. The line seize module includes its own input/output communication port connected to the wiring of the local telephone line and as such, is in direct communication with the alarm unit. Communication is separate and distinct from normal telephone communication and preferrably is at a high frequency above the audible range. This allows the alarm system to communicate between components while still allowing full conventional use of the telephone lines. The line seize module also includes control logic, a line seize arrangement and an automatic dialer. When an alarm condition occurs, the alarm unit transmits a signal to the line seize module which then takes appropriate steps to contact the remote monitoring station via the telephone system. This two part alarm system which communicates over the existing telephone wiring, reduces the vulnerability of the system to defeat.