AudioCodes Mediant 2000, Руководство пользователя

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Version 5.6 393 November 2008
SIP User's Manual 9. Advanced PSTN Configuration
9 Advanced PSTN Configuration
This section discusses advanced PSTN configurations.
9.1 Clock Settings
In a traditional TDM service network such as PSTN, both ends of the TDM connection must
be synchronized. If synchronization is not achieved, voice frames are either dropped (to
prevent a buffer overflow condition) or inserted (to prevent an underflow condition). In both
cases, connection quality and reliability is affected.
The device's clock settings can be configured to one of the following:
„ Generate its own timing signals
„ Use an internal clock
„ Recover a clock from one of the PSTN E1/T1 trunks
¾
To use the device's internal clock source, configure the following
parameters:
„ TDMBusClockSource = 1
„ ClockMaster = 1 (for all trunks)
¾
To use the recovered clock option, configure the following
parameters:
„ TDMBusClockSource = 4
„ ClockMaster_x = 0 (for all ‘slave’ trunks connected to PBX#1)
„ ClockMaster_x = 1 (for all ‘master’ trunks connected to PBX#2)
The above assumes that the device recovers its internal clock from one of the ‘slave’ trunks
connected to PBX#1 and provides clock to PBX#2 on its ‘master’ trunks. In addition, it's
necessary to define from which of the ‘slave’ trunks the device recovers its clock:
„
TDMBusPSTNAutoClockEnable = 1 (device automatically selects one of the
connected ‘slave’ trunks)
- Or -
„ TDMBusLocalReference = # (trunk number, where 0 is the first trunk - and the default)
Notes:
•
To configure the TDM Bus Clock Source parameters using the Web
interface, refer to ''Configuring the TDM Bus Settings'' on page
218 .
•
When the device is used in a ‘non-span’ configuration, the internal device
clock must be used (as explained above).