GB1143667A - - Google Patents

Abstract

1,143,667. Automatic exchange systems. INTERNATIONAL STANDARD ELECTRIC CORP. 9 Dec., 1966 [10 Dec., 1965], No. 55221/66. Heading H4K. In a P.A.B.X. employing cross-bars or reed relay matrices either party to an existing connection can, by signalling to the feedbridge to which and from which originating and terminating parts of the connection are set up, cause both parties to be connected to a conference circuit, the former connection via the feedbridge being released. A third party is called up and added to the conference by dialling into the conference circuit or alternatively the seizure of a conference circuit and the calling and adding the third party may be made in response to dialling the third party's identity by either party of the two-party connection. In addition a conference circuit may be reacted by a subscriber without first setting up a two-party call. As shown in the Figure, a feedbridge JVS upon receiving a conference request signal-an earth pulse applied by a special substation keyinforms a conference control KOST which receives the identity from identifier JdE of the two parties of the connection set up via the feedbridge JVS and controls a marker M to establish connections between a free conference circuit KOUe and each party over switches KA, KB, KC and KD. The former two-party connection is then released. A register KORg is taken into use by the conference circuit and the identity of the third party dialled with it, to whom a connection is then made. Failure of the third party to reply after a given period of ringing automatically causes the connection to the third party to be released or, alternatively, release may be instigated by one of the two existing confercees dialling the identity of the third party again. To add further conferees, the register must be reseized for each one by sending the conference request signal. Each conference input becomes available again upon a conferee hanging up. If the conference controller KOSt has its own digit receiving facility or has direct access to the exchange receivers the conference circuit is seized and a connection to a third party set up in response to the dialling of the identity of the wanted third party. Particular conference circuits can be seized by sending particular conference request signals.