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Cabling Diva Media Board PRI

Cable termination

If your Primary Rate line uses twisted-pair wires but the termination is not an RJ-45 socket, then you need to terminate the RJ-45 to bare-wire cable (included in some Diva PRI packages) with the correct connector, using the following description:

PRI Cable lengths

If the supplied cable is not long enough, be sure to use a single shielded cable of similar high quality grade to the cable supplied with the Diva PRI.

PRI cabling is more susceptible to signal interference and degradation than BRI because of the higher frequencies used..

The supplied cable is a straight-through, shielded Category 5 cable, with shielded connectors.  Long unshielded Category 5 cabling can cause problems, particularly in proximity to electrical or electronic equipment. 

There are no consistent standards for PRI cabling (as there are for BRI S-bus cabling) so it is not possible for us to give more than general advice on the length of cables.  It is often possible to use a cable up to 100m long, as long as good quality shielded cable is used, but this cannot be guaranteed in all circumstances.

Cable specifications

European - Telcos (or PBXs) implmenting EuroISDN use the PRI pin-out for PRI lines, which follows the I.431 specification for PRI lines.  This layout is also used in other parts of the world where EuroISDN is implemented.

DIVA PRI Card (RJ-45)            Telco PRI-Line termination
Pin 1 (Rx+) <--------------------------- Pin 1 (Tx+)
Pin 2 (Rx-) <--------------------------- Pin 2 (Tx-)
Pin 4 (Tx+) ---------------------------> Pin 4 (Rx+)
Pin 5 (Tx-) ---------------------------> Pin 5 (Rx-)

North American - Telcos (or PBXs) typically use the BRI pin-out for PRI lines, following the I.430 specification for BRI lines.

DIVA PRI Card (RJ-45)            Telco PRI-Line termination
Pin 1 (Rx+) <--------------------------- Pin 4 (Tx+)
Pin 2 (Rx-) <--------------------------- Pin 5 (Tx-)
Pin 4 (Tx+) ---------------------------> Pin 3 (Rx+)
Pin 5 (Tx-) ---------------------------> Pin 6 (Rx-)

Please bear in mind that while Telcos implementing EuroISDN will normally use the I.431 specification when they present the PRI line on an RJ-45 socket, if they use the G.703 (coax) method and you use a 'balun' or 'media converter', then the converter may present either an I.430 interface or an I.431 interface. Check the documentation for the balun for more information.

Example proprietary interface

When using a PRI line attached to a PBX, then the PBX manufacturer may implement various pin-outs that differ from both the ITU standards. One such example is attaching a D PRI card to a Lucent Definity PBX. Below is the pin-out for this PBX;

DIVA PRI Card (RJ-45)            Definity PRI-Line termination
Pin 1 (Rx+) <--------------------------- Pin 3 (Tx+)
Pin 2 (Rx-) <--------------------------- Pin 6 (Tx-)
Pin 4 (Tx+) ---------------------------> Pin 5 (Rx+)
Pin 5 (Tx-) ---------------------------> Pin 4 (Rx-)

See also:

• Diva PRI installation issues
• Diva PRI loop-back test