Tag-Length-Value block. A standardized block that allows data to inserted in a standard way into API messages.

Session-Initiation Protocol. A signaling protocol used for establishing sessions in an IP network. A session could be a simple, two-way telephone call, or it could be a collaborative multi-media conference session.

Voice over Internet Protocol. The delivery of voice information in digital form in discrete packets rather than in the traditional circuit-committed protocols of the public-switched telephone network (PSTN).

The point in the Excel platform where a DS0 connects to a network. Also known as a "socket."