I have a STS installed at a church and they want to have the door box feature along with being able to unlock the door from the phone. I've done the door box's but never the door lock/relay. The alarm guy says he can install the lock but I would need to provide the interface to the phone system. I see there is a "free relay" on the CO board, last pair; I also see there is a programmable feature for a "relay" (Sta, CO, Ext page) Are they the same? Is that what I would interface with? How does the staff person access the relay? Thanks for any input.