The BRI trunk card provides 4 Basic Rate ISDN S/T-Bus interfaces (8 trunks).
ISDN Basic rate provides 2 x 64K speech channels using Q.931 signaling and CRC error checking. Both point to point and point to multipoint operation is supported. Multipoint lines allow multiple devices to share the same line, however point-to-point is the preferred mode.
Basic rate supports all the services that are supported on the primary rate version with the addition of:
Multiple Subscriber Number - This service is usually mutually exclusive with the DDI/DID service and provides up to 10 numbers for routing purposes, very similar to DDI/DID.