CONFERENCE TELEPHONE SYSTEM

PURPOSE:To reduce the number of relay lines occupied with the connection to the conference, by providing a means setting the connection to the conference among subscribers to a relay exchange, in an automatic exchange network. CONSTITUTION:A relay exchange Px is provided with a conference trunk CFT. In executing the prescribed operation from a subscriber A1 to A2, channels C12 and C13 are released in the relay exchange Px, C11 and C14 are set, a relay trunk PVT3 is connected to an outgoing register trunk OGT, a PVT4 is connected to the trunk CFT. When the A1 dials a prescribed specific number and the number of A3, after a channel C19 is set, a PT5 and an OST are connected, the number of A3 from the OST is transmitted, the channel to the A3 via a relay line L3-1 and an exchange P3 is set, the channels C13 and C19 are released, C15 and C16 are set, A1 and A3 are connected. When the subscriber A1 executes the prescribed operation, the channels C15 and C16 are released, C17 and C18 are set, the PVTs 3 and 5 are connected to the conference trunk CFT and the operation is finished.