3.2. ISDN Basic Rate Interface (BRI) connection

3.2. ISDN Basic Rate Interface (BRI) connection
	Chapter 3. Physical connections

The Abilis ISDN-BRI ports are electrically configured like Telecom NT1 ports, so:

To connect the ports to “Terminal Equipment” systems (telephone switchboards, TA, ISDN modem, FAX …) you must use a straight cable cat.5. Set up the ports at a logical level as NT (Network Termination) in the Abilis configuration.
To connect the ports with the Telecom lines, you must use a “cross-cable (crossed) cat.5” (usually provided with red shells). Set up the ports at a logical level as TE (Terminal Equipment) in the Abilis configuration.

	Warning
	The ports which are configured at a logical level as NT must always be connected to a 100 ohm impedance matching adapter.

Figure 3.2. Typical connecting scheme between Abilis - ISDN lines

Tip

Interesting chapters:

Section 2.10.1, “QPRIX”;

Section 2.10.3, “PB44X”;

Section 2.10.6, “BRI-HFC4 / BRI-HFC8”;

Section 81.1, “How to configure ISDN ports to connect PBX or ISDN lines”.

3.2.1. Emergency connection

If necessary (in case of damages, bad functioning, lack of electricity …) the user can manually by-pass Abilis and connect the switchboard to the Telecom network. Antek suggests the following procedure:

Disconnect the cable between the PBX switchboard and the impedance matching adapter.
Disconnect the cable between the Telecom line and the Abilis port, keeping the impedance matching adapter.
Connect the straight cable from the switchboard to the Telecom one using the impedance matching adapter.
Repeat this procedure for every line you want to by-pass.

Figure 3.3. Emergency procedure (by-pass Abilis)

	Tip
	To restore the telephone connections we suggest to write down precise instructions about the emergency procedure and keep them on hand in the switchboard room, available to technicians.

3.2.1.1. Switch

To make the by-pass easier Antek provides Section 2.11.7, “RJ Switch” on request.

Tip

Interesting chapters:

Chapter 19, RJS - RJ Switch;

Section 3.10.1, “Connection examples”.

3.2.2. Importance of the impedance matching adapters (ISDN Adapter)

When ISDN-BRI ports (e.g. BRI-HFC4, BRI-HFC8) are used, a line termination resistor (ISDN Adapter or impedance matching adapter) must be used to avoid signal reflections. One adapter per port must be used.

The Telecom NT1 Network-termination units and most of the PBX (switchboards) usually have already a line termination resistor. The Abilis BRI port doesn't have any.

Differences between a Point-to-Point connection and a Point-to-multiPoint connection:

Figure 3.4. ISDN Adapter

Point-to-Point (only one device can be connected): an impedance matching adapter is ALWAYS necessary.
Point-to-Multipoint:
- If Abilis is the only device to be connected to the network-termination unit of the S0 bus or if Abilis is the farthest device from the NT unit, the impedance matching adapter MUST be inserted.
- If Abilis isn't the farthest device, the impedance matching adapter MUST NOT be inserted.

	Warning
	The impedance matching adapter MUST be connected near the ISDN port of the Abilis (you can use the 10 cm cable provided with the Abilis).

	Warning
	The Improper connection of line terminations may cause disturbances like noisy conversations, data loss, line drops, and in general a poor and unstable service.

	Tip
	Interesting chapters: Section 81.1, “How to configure ISDN ports to connect PBX or ISDN lines”.


3.1. Numbering of the physical ports		3.3. ISDN Primary Rate Interface (PRI) connection