ISDN BRI Recommendations 189ISDN BRIRecommendationsWhen you work with the telephone company to install an ISDN BRIcircuit, 3Com recommends the parameters discussed in the followingsections.■ Interface — The BRI connection supplied by the telephone companymust terminate at an S/T interface. Connections terminating at the Uinterface are not supported.■ Point-to-Point and Point-to-Multipoint — Both point-to-point andpoint-to-multipoint configurations are supported.The appropriate TEI (Terminal Endpoint Identifier) must be enteredwhen configuring the BRI card. Typically, Automatic TEI assignment isused on Point-to-Multipoint lines. For Point-to-Point lines, set the TEIvalue to 0 (zero).By default the system is configured to use Automatic TEI assignment.Thus, if the line provided is Point-to-Point, this will typically mean theTEI has to be set to 0 (zero) when configuring.■ DDI/MSN Applications — For DDI/MSN, 3Com recommends thatyou order telephone numbers that easily fit in the NBX systemnumbering plan. If possible, use 3 or 4 digit DDI/MSN codes, whichallow for simple dial plan implementation.■ With 3 digit extensions 100-499, the last three digits of theDDI/MSN codes should be 100-499.■ With 4 digit extensions 1000-4999, the last four digits of theDDI/MSN codes should be 1000-4999.■ Supported Telephone Central Office Switch Protocols — NBXsystem ISDN BRI services support the ETSI central office switchprotocol.
