Toshiba Strata CT, Инструкция по установке и обслуживанию

Страница: 335 / 385

ISDN Interfaces
Strata CT I&M Manual October 2000
10-9
Overview
The RBSU and RBSS PCBs provide the Basic Rate Interface (BRI) circuits for Strata CT.
The RBSU is the main plug-in PCB that plugs into the Strata CT cabinet slots.
The RBSS is an optional PCB that plugs onto the RBSU. Each PCB provides two ISDN BRI
circuits. Each BRI circuit provides 2 B-ch 1D channel for voice/data/video
applications.
An REBUIA PCB is a piggy-back PCB that plugs onto the RBSU and provides basic
functions for RBSU/RBSS circuits so it must always be installed on the RBSU. This card is
not supplied on RBSU.
The RBSU circuits are four-wire S/T type circuits and connect to the Public Switched
Telephone Network (PSTN) BRI lines using an Network Terminator unit (NT1); or, on the
station side, they can connect to ISDN Terminal Equipment (TE) or Terminal Adapters (TA)
as shown in
Figure 10-5 .
TE devices include any ISDN device (telephone, fax, computer) that connects directly to S/T
ISDN BRI circuits. TA devices match the protocol of non-ISDN devices (telephone, fax,
computer) to the protocol of S/T ISDN BRI circuits.
The RBSU circuits can be configured two ways:
◆
As BRI – TE circuits which connect to Telephone Network BRI lines using a NT1.
◆
As BRI – NT circuits which connect to ISDN TEs or TAs. These devices must be S-type
station devices.
Important!
In Strata CT, each BRI circuit consumes two line numbers and two station port
when configured as line-side or station side on the RBSU. Circuits installed on
the RBSS use only station ports.
The RBSU connection options (BRI line or ISDN TE-1/TA devices) are selected in Strata CT
customer database programming and option switches located on the RBSU.
The RBSU circuits that connect to the ISDN network side requires a NT1 interface box to
convert the two-wire, U-interface BRI line from the telephone network to the four-wire, T-
interface of the RBSU circuit. The network BRI line connection is a point-to-point
connection, which means that the network BRI line can only be connected to one RBSU
circuit via the NT1 (T-reference point).
RBSS circuits connect directly to S-type ISDN devices only. They do not support BRI-TE
telephone network BRI line connections.
The RBSU, and/or RBSS circuits that connect to the CT station side, (BRI-NT, S-reference
point) allows direct connection of multiple ISDN (TE-1 or TA) devices. The S point of the
RBSU/RBSS supports the Toshiba CT passive bus, also known as point-to-multipoint
connection. The terminal-side (S-point) of the RBSU/RBSS BRI circuit can have parallel
connections of up to two TE-1s or TAs maximum.
When multiple TE-1 and TA devices are installed on a single RBSU/RBSS BRI circuit, the
devices must share, or contend for, that circuit’s two B-channels. That is to say, a maximum
of two simultaneous voice and/or data calls are allowed between both devices connected to
the same BRI circuit. The contention rule for the two BRI B-channels is first come, first
served.
H
C