ISN T8 is for Unshielded Telecom Lines. Its design is based on the circuit illustrated in Figure D.3 of CISPR 22 and Figure F8 of CISPR 32. The RF Port is a 50 Ohm female BNC connector, located on the top of the ISN. The ISN is equipped with two D-sub 25 pin female connectors located on the front panel (EUT Port) and rear panel (AE Port), providing the interface to the LCL Adapter and Connecting Adapter, respectively.