BRIDGE CONNECTION SYSTEM FOR INTER-OFFICE LIAISON TELEPHONE LINE

摘要

PURPOSE:To avoid a trouble of a crosstalk/busy state by providing a telephone line bridge network to each small area having a high talking frequency. CONSTITUTION:Inter-office liaison telephone line bridge networks (district line networks) 1a, 1b,... are set for each of districts A, B,... being small areas with high talking frequency. Key stations Ka, Kb,... are in bridge connection by an optical trunk line 10 in one stroke writing. There is no usual connection between the optical trunk line 10 and the district line networks 1a, 1b,..., but when a call obtaining the talking with a terminal station of other district line network comes, the relevant key station connects the district line network to the optical trunk line. After the end of communication, the connection is interrupted. Thus, spur expansion connection is executed without a limit and the occurrence of crosstalk or busy state is possibly decreased.