摘要 |
A system for electronically selecting and establishing test loop circuits between a remote test position and any of a large number of communication lines at an access location. Extensive logic circuits at the access end and the test end exchange information and display for the operator if the circuit is ready, if there has been a transmission error or component failure, if the circuits are busy, and other factors that affect the system thereby making the operator's task easier. Fail safe circuits prevent opening of telephone lines by access circuitry malfunctions. |