3Com 3C10200 NBX Installation Guide - Page 227

ISDN BRI Recommendations 227 ISDN BRI Recommendations When you work with the telephone company to install an ISDN BRI circuit, 3Com recommends the parameters discussed in the following sections. ■ Interface - The BRI connection supplied by the telephone company must terminate at an S/T interface. Connections terminating at the U interface are not supported. ■ Point-to-Point and Point-to-Multipoint - Both point-to-point and point-to-multipoint configurations are supported. The appropriate TEI (Terminal Endpoint Identifier) must be entered when configuring the BRI card. Typically, Automatic TEI assignment is used on Point-to-Multipoint lines. For Point-to-Point lines, set the TEI value 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 the TEI has to be set to 0 (zero) when configuring. ■ DDI/MSN Applications - For DDI/MSN, 3Com recommends that you order telephone numbers that easily fit in the NBX system numbering plan. If possible, use 3 or 4 digit DDI/MSN codes, which allow for simple dial plan implementation. ■ With 3 digit extensions 100-499, the last three digits of the DDI/MSN codes should be 100-499. ■ With 4 digit extensions 1000-4999, the last four digits of the DDI/MSN codes should be 1000-4999. ■ Supported Telephone Central Office Switch Protocols - NBX system ISDN BRI services support the ETSI central office switch protocol.