Arrangements for signalling the number or class of the calling line to the operator

Full Title

Automatic or semi-automatic exchanges > Semi-automatic systems, i.e. systems in which the numerical selection of the outgoing line is under the control of an operator > Arrangements for signalling the number or class of the calling line to the operator

Classification Context

Section:

ELECTRICITY

Class:

ELECTRIC COMMUNICATION TECHNIQUE

Subclass:

TELEPHONIC COMMUNICATION