Control system for telephone switching system

In a telephony system including a plurality of telephones and interconnecting telephone lines for conveying signals from and to said telephones and call processing means connected to said telephone lines for selectively interconnecting the telephones and respective lines to establish communications between pairs of telephones, and wherein the call processing means includes a port means that connects to each telephone line and selective switching means for interconnecting selected pairs of the port means, the improvement of automatic test call means for testing the operation of the selective switching means, said automatic test call means comprising:

• A. Selectable test access means in each port means and connected to the corresponding telephone line for coupling signals from and to the telephone lines and for isolating the port circuit means from the telephone lines,
• B. test call generating means for generating signals corresponding to telephone line signals during a calling operation,
• C. control means connected to said selectable test access means and said test call generating means for selecting a first test access means and a second test access means thereby to establish an input and output path for the signals from said test call generating means, whereby the call processing means processes the telephone test call between the selected port circuit means, and
• D. test call monitoring means selectively connected to said second test access means for monitoring the signals at said second test access means during the test call.

A telephony system for routing communications over a plurality of telephone lines, said system comprising:

• A. port means connected to the telephone lines for receiving signals therefrom and for transmitting signals thereto,
• B. first and second parallel, independently and synchronously operable call processing means for interconnecting, on a selective basis, certain of the telephone lines, each said call processing means operating concurrently in response to the same signals from the port means by generating output signals,
• C. controllable switching means interposed between said port means and both said call processing means for coupling the output signals from a selected one of said call processing means to said port means to complete communications between said port means and the selected one of said call processing means,
• D. selectable test access means in each said port means connected to the corresponding telephone and telephone line for coupling signals from and to said telephone lines and for isolating said port means from the telephone lines,
• E. test call means connected to said selectable test access means for effecting test calls through the selectable test access means, said test call means comprising:
• i. test call generating means for generating signals corresponding to telephone line signals during a calling operation,
• ii. control means connected to said selectable test access means and said test call generating means for selecting a first test access means and a second test access means for establishing an input and an output path for the signals from said test call generating means, whereby said call processing means processes the telephone test call between the selected port means, and
• iii. test call monitoring means selectively connected to said second test access means by said control means for monitoring the signals at said second test access means during the test call,
• F. fault monitoring means connected to each said call processing means for generating fault signals in response to fault conditions in said call processing means, including fault signals generated in response to a test call, and
• G. switchover means connected to said fault monitoring means, said controllable switching means, said test call monitoring means, and both said call processing means and operable independently of both said call processing means thereby to test each said call processing means in response to certain of said fault signals and identify one of said call processing means as the source of the fault condition and to cause said controllable switching means to couple output signals from the other of said call processing means to said port means.