Clock Settings; Recovering Clock From Pstn Line Interface - AudioCodes Mediant 3000 User Manual

User's Manual
3. Click Submit.
4. Save the changes to flash memory, see ''Saving Configuration'' on page 580.

22.2.4 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.

PSTN line clock (see ''Recovering Clock from PSTN Line'' on page 365)

BITS synchronization (see Configuring BITS Synchronization Mode on page 366)

Internal clock (see ''Configuring Internal Clock as Clock Source'' on page 367)
Note:
must be used (as explained above).

22.2.4.1 Recovering Clock from PSTN Line Interface

This section provides a brief description for configuring synchronization based on
recovering clock from the PSTN line interface. For a full description of the clock
parameters, see ''PSTN Parameters'' on page 865.

To configure synchronization based on clock from PSTN line:
1. In the System Timing page, do the following:
a. Set the 'TDM Bus Clock Source' parameter (TDMBusClockSource) to Network to
recover the clock from the line interface.
b. For E1/T1 trunks only: Select the trunk from which the clock is derived, using the
'TDM Bus Local Reference' parameter (TDMBusLocalReference).
Note:
description of the 'Clock Master' parameter).
c. For E1/T1 trunks only: Enable automatic switchover to the next available "slave"
trunk if the device detects that the local-reference trunk is no longer capable of
supplying the clock to the system:
a.
b.
c.
d. If the device has BITS capability, set the 'Timing Module Mode' parameter
(TMMode) to LineSync to use the line interface clock.
2. For E1/T1 trunks only: Set the PSTN trunk to recover/derive clock from/to the remote
side of the PSTN trunk (i.e. clock slave or clock master): In the Trunk Settings page,
Version 6.8
When the device is used in a 'non-span' configuration, the internal device clock
The E1/T1 trunk should recover the clock from the remote side (see below
Set the 'TDM Bus PSTN Auto FallBack Clock' parameter
(TDMBusPSTNAutoClockEnable) to Enable.
Enable the device to switch back to a previous trunk that returns to service if
it has higher switchover priority, using the 'TDM Bus PSTN Auto Clock
Reverting' parameter (TDMBusPSTNAutoClockRevertingEnable).
In the Trunk Settings page, configure the priority level of the trunk for taking
over as a local-reference trunk, using the 'Auto Clock Trunk Priority'
parameter (AutoClockTrunkPriority). A value of 100 means that it never uses
the trunk as local reference.
365
22. Digital PSTN
Mediant 3000