
TD 92326GB
2009-03-10 / Ver. E
Installation and Operation Manual
VoIP Gateway
51
9
PRI Interfaces
The VoIP Gateway has four ISDN PRI interfaces. They are labelled PRI 1 to PRI 4. All four PRI
interfaces are by default in TE mode but can be set in NT mode. See
• PRI 1 to PRI 4 are primary multiplex (PRI) interfaces in TE mode for the connection to a
PBX or a public exchange line.
• PRI 1 and PRI 2 (as well as PRI 3 and PRI 4) can be linked, which can be used for looping
the exchange line when power is off.
To configure the ISDN interfaces you first need to decide which devices you want to
connect to the VoIP Gateway. That could be telephones, PBXs, network terminations from
your ISDN network provider, or other ISDN terminal equipment.
9.1
Physical – Configuration of the Physical PRI Interface
All changes in the settings except
Swap tx/rx
,
Do not use for synchronization
and
Relay off
requires a reboot of the VoIP Gateway (the “Reset is required” link will appear).
1
Select PRIn > Physical.
Figure 45. PRI physical configuration
2
Select/Enter the following settings.
Figure 53.
Field name
Description
• NT Mode
The PRI interfaces are default in TE (Terminal) mode but
can be set in NT (Network Termination) mode, see
• Clock Mode
Default the VoIP Gateway synchronises itself to the
network clock (clock slave) in TE mode, and provides the
clock (clock master) in NT mode, but this can also be
manually selected.
• Swap tx/rx
Swaps the receive leads. Enable if you use a modified
(crossed) connection cable instead of a standard 1:1
ISDN connection cable.
• Do not use for
synchronization
Do not use this PRI as a clock source.
• µ-law
Changes from A-law encoding to µ-law encoding.
• T1
Changes from E1-mode to T1-mode.