Toshiba Strara CTX Series, Installation And Maintenance Manual, Page: 166 / 290

ISDN Interfaces
5-18
Strata CTX I&M September 2002
In the U.K., the BRI line from the ISDN service provider is a two-wire U-type BRI line. This line
connects to the RBSU TE circuit via a customer-provided NT1 as shown in
Figure 5-15 . The NT1 is
necessary to convert the network BRI, two-wire, U interface to the RBSU BRI, four-wire, T interface.
The connection between the NT1 and the RBSU TE circuit is a point-to-point connection, so the NT1
can connect to only one RBSU BRI TE circuit.
A 100-ohm Terminating Resistor (TR) is required at one end of the point-to-point connection. The TR
must be switched into the RBSU TE circuit (refer to option switches in
Table 5-6 on Page 5-16 and
Table 5-3 on Page 5-12 ) and off at the NT1 device or vice-versa.
The maximum loop length between the NT1 and the RBSU circuit is 400 meters using CW1308 or 800
metres using CW1700/1750 or equivalent.
Figure 5-15 RBSU to NT1 Point-to-point Connection
Connecting RBSU/RBSS Station Devices (NT-Mode)
S-type TAs and TE-1s can be connected to the station side of RBSU and RBSS circuits. TA and TE
devices must be powered by local AC power using AC adapter supplied with the TA or TE device. The
RBSU/RBSS circuits must be configured in the NT mode when connected to TA and TE devices (refer
to option switches in
Table 5-3 on page 5-12 and Table 5-6 on page 5-16 ).
The TA enables you to connect non-ISDN voice and data devices to ISDN BRI circuits. The TA
matches the protocol of existing interfaces (R-reference point) to the ISDN S/T protocol (see
Figure
on page 5-2 ). TA devices include asynchronous circuit-switched adapters that convert RS-232 sync
data (like data from a PC COM port) to B-channel 64 kbps sync.
TAs also enable you to connect standard telephones and non-ISDN fax machines to receive and make
calls over ISDN circuits. TEs include any user device (telephone, fax, PC video conference board) that
is designed to plug directly into the ISDN (S/T) interface without the use of a TA.
RBSU
TE-Circuit
Switch in
100-ohm TR
using RBSU
option switch.
RJ45 Pinout
(RBSU - BRI jack)
5433
Network
BRI-line
RJ11 Jack
NT-1
Switch
in 100-ohm
TR.
T and U are ISDN standard
reference points. Note:
BRI
(four-wire)
T
BRI
(two-wire)
U
Demarcation Point
3
6
4
5
3
6
4
5
RX
RX
TX
RX TX
TX
RX TX
RX/TX
RX/TX 4
5
RJ45 Pinout
(NT1 - S/T jack)
Local AC
Power