Warm Line
Warm Line sets your phone so that it will automatically dial a number you choose whenever the phone is left off the hook for more than 30 seconds.
In the event of an emergency, or if you were unable to speak or dial, simply open your phone line (get a dialtone) and, after thirty seconds, the number you pre-programmed into the Warm Line will be dialed.
Typically the pre-programmed number is to an emergency agency, a friend, or a relative.