H04M9/00—Arrangements for interconnection not involving centralised switching
H04M9/002—Arrangements for interconnection not involving centralised switching with subscriber controlled access to a line, i.e. key telephone systems
H04M9/005—Arrangements for interconnection not involving centralised switching with subscriber controlled access to a line, i.e. key telephone systems with subscriber controlled access to an exchange line
Landscapes
Engineering & Computer Science
(AREA)
Signal Processing
(AREA)
Sub-Exchange Stations And Push- Button Telephones
(AREA)