134 CHAPTER 6: BRI-ST D IGITAL L INE CARDAdding a BRI-STDigital Line CardTo add an ISDN BRI-ST Digital Line Card to an NBX system, use theinformation in these sections:■ Preparing the NBX System for BRI Cards■ Ordering DID, CLIP, and MSN Services for BRI■ Inserting the BRI-ST Digital Line CardPreparing the NBXSystem for BRI CardsBefore you insert the BRI-ST Digital Line Card into the chassis, order anISDN BRI-ST line from your telephone carrier and have them install it.Ordering DID, CLIP,and MSN Services forBRIWhen you order BRI services with DID, CLIP, or MSN, the local telephonecarrier assigns a block of telephone numbers to you. You may be able torequest that the local telephone carrier pass you a specific number ofdigits for each incoming telephone call. Sometimes the carrier does notoffer any choice. In either case, you need to know how many digits thecarrier passes.Example: Carriers commonly pass either the last three digits or last fourdigits of the number for each incoming call.Sometimes the last digits of the telephone numbers the carrier assigns toyou do not match the telephone extension numbers you want to use forinternal calls. You can create entries in your Dial Plan file to translate theincoming numbers into the corresponding extension numbers.Example: You want to use internal extensions from 4000 through 4999,but the local telephone carrier assigns you numbers from 617-555-3500through 617-555-4499. You can create translator entries in the Dial Planconfiguration file to translate an incoming digit sequence such as 3795into extension number 4295, and a sequence such as 4213 into 4713.The configuration would require several translator entries to handlesubsets of the total range. A unique set of entries would handle incomingdigit sequences from 3500 through 3599, from 3600 through 3699, andeach of the other sequences in which the first two digits were unique inthe range from 37XX through 44XX.If the DDI/DID numbers match your internal extension numbers, thetranslator entries in your Dial Plan configuration file can be much simpler.Example: You plan to use internal extensions from 100 through 299,and the local telephone company assigns you numbers from
