64 / Welcome to ISDNModular ICS 7.1 Installer Guide N0130943 02DTI card configured as a PRI cardThe DTI card on your Norstar system can be configured tosupport PRI. For information about configuring a DTI card asa PRI type card, see Provisioning the DTI card for PRI on page497.ISDN hardwareTo support connections to an ISDN network and ISDNterminal equipment, your Modular ICS must be equipped withone or more BRI cards (BRI-U or BRI-ST), a DTI cardconfigured for PRI, and a Combination Fiber 6-port ServicesCartridge or a Services Cartridge.DTI card configured as PRIA DTI card configured as PRI provides one T loop. Refer toT reference points on page 68 for more information.In most PRI network configurations, you need one DTI cardconfigured as PRI in your ICS to act as the primary clockreference. The only time when you may not have PRIdesignated as the primary clock reference is in a networkwhere your Norstar system is connected back-to-back withanother switch using a PRI link, such as is the case with theAdvanced Private Networking configuration.However, if the other switch is loop-timed to your Norstarsystem, your DTI card, configured as PRI, can be designatedas a timing master.If your Norstar has two DTI cards configured as PRI, youcannot assign both cards as the primary reference or both cardsas the secondary reference. You can only have one primaryreference and one secondary reference per system. Refer toClockSrc on page 506 for more information.
