Installing ISDN BRI terminal equipment / 295N0130943 02 Modular ICS 7.1 Installer GuideS or T extension wiring configurationsThe last connection on any ISDN S or T extension wiring musthave terminating resistors to ensure correct timing of thesignaling circuits. Failure to install terminating resistors willdegrade performance. Terminating resistors should not beconnected on a TE which is not the last connection on the loop.Terminating resistors are provided on terminal equipment. Seethe instructions that come with your TE for information abouthow to enable or disable the termination, as required.The maximum length of spur and ISDN connection cord(the extension from the main line or bus) is 10 m (30 ft).Refer to S reference point on page 67 and T reference pointson page 68 in the Welcome to ISDN chapter for informationabout wiring arrangements for ISDN terminal equipment (TE)on an S or T loop.Additional powerA Norstar S or T-loop does not provide power on PowerSource 1 (PS1), Power Source (PS2), or Power Source orSink 3 (PS3). If you are installing ISDN terminal equipment atthe S-reference point, and the equipment requires additionalpower on PS1, PS2, or PS3, then you can install a suitably-approved power supply unit. See ANSI T1.605 or thedocumentation that comes with your TE for details.The Modular ICS does not require power on PS3.Wiring arrangements using side circuits, also called phantomcircuits, may affect loop performance when they are used toprovide power to the TE (PS1). You must account for anyeffects. For example, you may need to reduce the number ofTEs on a passive bus.
