When the digital communicator is active, what is the voltage across terminals 1 and 6 of a RJ31X connector?

When the digital communicator is active, what is the voltage across terminals 1 and 6 of a RJ31X connector?

• A. 0V
• B. 7V to 9V
• C. 12V
• D. 15V

Answer: (B)

A small DC bias is placed on the telephone line by the digital communicator to supervise the line and power its signaling, and on the RJ31X’s terminal pair this appears as about 7–9 volts when the device is active. This modest voltage is intentional and keeps the line in a controlled state during outbound transmission, without pushing a full line supply through the interface. That’s why 7–9V is the correct range. Zero volts would mean no active bias, while higher voltages like 12V or 15V aren’t the standard bias produced by the interface in this active mode.

A small DC bias is placed on the telephone line by the digital communicator to supervise the line and power its signaling, and on the RJ31X’s terminal pair this appears as about 7–9 volts when the device is active. This modest voltage is intentional and keeps the line in a controlled state during outbound transmission, without pushing a full line supply through the interface. That’s why 7–9V is the correct range. Zero volts would mean no active bias, while higher voltages like 12V or 15V aren’t the standard bias produced by the interface in this active mode.