Voice Transmission Through Local Area Networks (01-Oct-1985)

Voice Transmission Through Local Area Networks

Local Area Networks (LANs) can be used for digital voice transmission. Assume that a 4 megabits/sec LAN is available. Voice signals provided by telephone sets are processed by segments of 5 ms into voice terminal units and then segments are assembled into a packet having a high level data link control (HDLC) (or synchronous data link control (SDLC)) format within a voice terminal equipment. Each packet includes headers wherein the addresses of both sending and destination voice stations are inserted. The voice terminal equipment (VTE) could be attached to the LAN through adapters (A). The routing of packets is performed on the local area network using the physical address of each connected station. In order to comply with that protocol each VTE will give to each packet (call or information packet) the destination address. On top of that, in order to allow an acknowledgement and a routing within the VTE of the destination, it will indicate its own address (origin) and the address of the entry gate. Both the origin address and the destination address define one virtual link. Instead of a centralized PBX with star connection of the telephone sets, each telephone set is connected directly or through a cluster (VTE) to the local area network. The connection to trunks or tie lines is done by using a specialized cluster.

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