Telephone wiring modes refer to the wiring configurations used to connect auxiliary apparatus such as alarm panels, fax machines, data equipment, auto dialers, etc to an existing telephone service. Mode 3 is by far the most commonly used configuration with 611 sockets commonly (and erroneously) often referred to as a Mode 3 socket.
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Note 1: If an earth is required for recall etc, connect it to the telephone as shown thus - - - -. If an earth is required on the auxiliary equipment it is connected as shown thus -x-x-
Note 2. Connection to these terminals is required only where the auxiliary equipment incorporates facilities for switching the line to the telephone.
Note 3. Where the telephone is connected to a 4 wire extension from a PABX, terminate the fourth wire on terminal 4 of the 611 socket.
Note 4. Cams 1-2 & 5-6 are in the normally closed position. Cam 3-4 is in the normally open position.