Telephone line transfer circuit

Abstract From the Canadian patent

Transfer of an incoming call on a first telephone line for a first subscriber set to a second independent telephone, line for a second subscriber set is accomplished without permitting a party at the first subscriber set to listen to the transferred call. An adjustable time delay circuit causes the tip and ring leads of the first central office telephone line to be switched to the second subscriber set after a predetermined, amount of ringing at the first subscriber set. If the second subscriber set is in use or is being rung at the time a transfer is to take place, no switching occurs. If the first subscriber set is answered before the present time delay is elapsed no, switching occurs. …