ITU-T V.251 PDF

Introduction and scope

Recommendation V.8 is standardized for use in negotiating the call type at the beginning of a PSTN call. Recommendation V.8 bis is standardized for use in negotiating the call type during a PSTN call. They provide means to select amongst several single media or multimedia operating modes.

• data modem (V-Series modems);

• text telephone (Recommendation V.18);

• send G3 facsimile (from calling terminal);

• receive G3 facsimile (polling);

• simple voice telephony;

• analog simultaneous Voice and data;

• digital simultaneous Voice and data;

• multimedia terminal (e.g. Recommendation H.324).

Means are defined in this Recommendation for use in DTE control of V.8 and V.8 bis call negotiation.

These means are designed so that the negotiation decisions are made in the DTE, so that compliant DCE do not need modification each time V.8 or V.8 bis code points are added or modified in other ways.