ITU-T Q.421-1988
Line Signalling, Digital Version - Digital Line Signalling Code - Specifications of Signalling Systems R1 and R2 (Study Group XI) 2 pp

Standard No.

ITU-T Q.421-1988

Release Date

1988

Published By

International Telecommunication Union (ITU)

Status

Withdraw

Latest

ITU-T Q.421-1988

Scope

Primary PCM multiplexes (see Recommendations G.732 and G.734) economically provide more than one signalling channel per speech circuit in each direction of transmission. By making use of the increased signalling capacity, simplification of the outgoing an

ITU-T Q.421-1988 history

• 1988 ITU-T Q.421-1988 Line Signalling, Digital Version - Digital Line Signalling Code - Specifications of Signalling Systems R1 and R2 (Study Group XI) 2 pp