ISDN systems provide two B channels and one D channel over a single twisted pair copper wire. Each B channel can carry voice, fax, or Internet calls at 64 kbps, whereas the D channel manages both B channels at 16 kbps.
An NTBA (Network Termination for Basic Access) is typically installed at the end user's house or office and connects to the main switchboard. The NTBA usually operates like a PBX system as you may need to dial a prefix number to gain access to the external dial tone, and can also make internal calls.
Typically ISDN providers allow a certain range of numbers. For example, if the ISDN provider assigns a user the phone number range between 100 - 110 (allowing 10 phone numbers), then it is up to the user to assign these numbers within the ISDN environment.
An A/D converter (analog/digital converter) allows analog devices to be installed on an ISDN network. The A/D converter routes the calls to the assigned analog ports, converts digital signals into analog, and allows analog equipment to communicate over ISDN.
Equipment installed on an ISDN network must be correctly tagged indicating the type of device (that is, a telephone, modem, or fax). Each analog port on the A/D converter must be programmed with the right tag.
ISDN fax setup
Connect the HP fax cable supplied with your HP All-in-One or fax product to the outlet labeled 1-LINE (or LINE) at the back (or on one side) of the HP All-in-One or fax device, as shown in the diagram above.
Connect the NTBA (Network Termination for Basic Access) to the telephone wall socket. Connect the A/D converter and, if applicable, other ISDN devices to the NTBA. To do so, use the instructions contained in their respective manuals.
Insert the other end of the HP fax cable into one of the A/D converter ports (analog outlets) according to the guidelines of the A/D converter manufacturer.
Insert a phone cable into your telephone according to the manual provided by the telephone manufacturer. Insert the other end of this telephone cable into a second A/D converter port (analog outlet) according to the guidelines of the A/D converter manufacturer.
Not all printers and faxes are compatible with ISDN services. HP does not guarantee that the HP All-in-One or fax device be compatible with all ISDN devices or manufacturers.
The NTBA and A/D converter may be integrated in a single box.
It is usually advisable to set the A/D converter port to Multicombi or Equal mode or equivalent. Follow the instructions in the A/D converter manual to program ports.
The port on the A/D converter can usually be programmed to get an external dial tone directly.
The HP All-in-One or fax device can be connected to any port on the A/D converter.
Some A/D converters can assign different fax numbers to the ports available. If your A/D converter provides this functionality, check the manuals provided by the manufacturer to learn how to do so.