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IP Office Installation Page 158
15-601042 Issue 20b (16 July 2009) IP Office
8. External Trunk Configuration
This section cover the basic requirements for external trunk configuration. The exactly method of physical connection and
configuration will vary with each trunk provider and so requires local telecoms experience. The topics covered here are
general guidelines.
•
Clock Quality
Altering which digital trunk is used to provide the IP Office with its clock signal for call synchronization.
•
Unused Trunks
Disabling the use of trunks and trunk channels that are not available.
•
Prefix Dialing
On systems where a prefix is being used for external dialing, ensuring that the same prefix is added to incoming
numbers in order to allow return calls.
8.1 Clock Quality
Any system where digital trunks are being used requires a clock signal for call synchronization between the switches at
each end of the trunk. Typically the clock signal provided by a digital trunk from the central office exchange is the best
quality and most reliable source.
The IP Office can obtain and use the clock signal from any of its digital trunks. However it will only use one trunk for its
clock signal at any time and will ignore any other possible clock sources. If no clock source is available the IP Office can
use its own internal clock if necessary.
The Clock Quality setting on each line is set to one of the following:
•
Network
If available, the clock signal from this trunk can be used as the IP Office's clock source.
•
Fallback
If available, the clock signal from this trunk can be used as the clock source only if none of the trunks set to
Network are providing a clock source.
•
Unsuitable
The clock source from this trunk is never used as the IP Office's clock source.
In the example below the first IP Office is set to use the public network trunk as its clock source and ignoring the possible
clock source from the QSIG trunk. However the other system is using the QSIG trunk as it clock source.
Source Priority
When multiple trunks with the same setting are providing a clock signal, the trunk used is determined in the following
order of priority.
•
Small Office Edition - Trunks are used in the order of ports 1 to 4.
•
IP400 Control Units - Trunks are used in the order Slot B ports 1 to 4, then Slot A ports 1 to 4.
•
IP500 Control Unit - Trunks are used in the order of slots 1 to 4 and then by port on each slot.
Viewing the Current Clock Source
The current clock source being used by an IP Office system is shown on the Resources page within the IP Office System
Status Application.