External synchronisation option – 2N StarGate/BlueTower v5.5 User Manual
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Figure: 1ISDN PRI Card Installation
External Synchronisation Option
There is an exact time source for synchronisation of the PRI interface lines on the PRI
board. Even if you have synchronisation problems on the installation site (caused by
specific and probably ill-configured PBXs with more that one active PRI interfaces),
there is a solution as shown below. Before using this solution you are recommended to
configure your PBX properly, or use the DialThru function.
Figure: Unnormalised External Synchronisation
Connect
to the 2PRI board because the ISDN PRI line is not designed for
only Tx wires
point-to-multipoint solutions (more than two devices on one ISDN line) like the BRI
ISDN line. This solution is substandard! In case you detect a problem on the line
between the PBX and PSTN (due to an additional connection to the PRI 2 interface),
please disconnect PRI 2 from the line. These problems may be caused by changes in
the line impedance.
Note
Connecting Tx wires only (from the PSTN point of view) to the PRI 2
interface has
on signalling and voice calls. The PRI board just
no influence
takes synchronisation pulses from the line.