Title:
ADD-ON SERVICE SYSTEM
Document Type and Number:
Japanese Patent JPS5222408
Kind Code:
A
Abstract:
PURPOSE: To make the mutual calling by more than three subscribers possible with the common utilization of the add-on scrivce unit with reduced installation number and the number of the terminals of channel network.
Inventors:
TOOYAMA TOSHIAKI
Application Number:
JP9763175A
Publication Date:
February 19, 1977
Filing Date:
August 13, 1975
Export Citation:
Assignee:
HITACHI LTD
International Classes:
H04M3/56; (IPC1-7): H04M3/56