ISDN-BRI Trunk Connections
Integrated Service Digital Network - Basic Rate Interface (ISDN-BRI) is a Public Switched Telephone Network (PSTN) service that provides two B channels and a D channel (2B + D) for voice call trunking. The B channels provide two CO/PBX connections. Caller ID is usually a standard feature on ISDN-BRI provided trunks. Caller ID indication displays the calling party telephone number on the LCD of the Multiline Terminal for CO incoming calls. This interface provides voice communication path only.
With System Software R1.03 or higher and BRI firmware 1.31 or higher, Caller ID Name is supported on ISDN-BRI trunks when the Telco provides this ability.
For R4000 or higher, BRT(4)-U20 with Firmware 3.00 or higher is required to support DID for ISDN-BRI trunks.
This feature allows BRI and DID callers with non-matching SPID Numbers to determine whether or not the system checks the called party number with the SETUP message and the SPID setup. Depending on Memory Block 3-77 (ISDN-BRI/PRI Directory Number Checking Selection) DID calls can be received on BRI trunks and directed according to Memory Block 1-1-22 (DID Translation Table).
Special Conditions Related to Ordering Did Service For ISDN-BRI
Telcos may refer to this in different ways. The reference Verizon uses to order such service is Additional Directory Numbers with no new terminating equipment (only a dialable number). When you want Additional Directory Numbers to hunt when a B-Channel is busy, the service may be called Busy Divers.

For AVAYA, NORSTAR, NEC, SAMSUNG, MITEL, PANASONIC, TOSHIBA telephone systems and voicemail call (866)206-2316 or email