Abstract:
In a multipoint data communications system a multipoint switch responds to polling signals on a signaling path from a central station by extending the signaling path to a selected one of a plurality of remote terminals. Thereafter the multipoint switch blinds itself to signals on the signaling path and remains blinded until there is an absence of signals on the signaling path for a predetermined interval of time. Communications apparatus at the selected remote terminal is enabled by a single frequency tone followed by a silent interval with the single frequency tone and the silent interval being common for all remote terminals.