Most T1, E1, and DDS circuit wiring inside customer premises uses unshielded twisted-pair (UTP) cable that is terminated with RJ-48 connectors. To verify correct operation of these circuits, it is often necessary to make a passive tap into the circuit at a location in the wiring where there is no monitor port available.
The Model 3/11 and Model 3/45 Data Taps can be used to quickly insert a passive tap into UTP wiring using RJ-11 or RJ-48 connectors. Once the Model 3 is inserted in-line in the UTP wiring, a test instrument may be attached to the box's tap connector and monitor communication on either of the two pair used for T1, E1, or DDS circuits.
The tap connections are made through 470-ohm resistors to minimize the possibility that a wiring fault at the tap will cause failure of the main line being monitored. All four pair in a typical UTP cable are tapped to allow use of the same box for different pair combinations. The Model 3 contains no active components, making it very reliable for use in continuous operation communication circuits.