How to configure the clock source for a trunk of the U1900 series unified gateway

1. If you use the CLI, run the following command to configure the clock source:
config system clocksource primaryslot 3 primarye1 0
Parameter description:
primaryslot: indicates the slot number of the DTU/MTU board connected to the trunk line through which the clock source is synchronized to the peer device.
primarye1: indicates the E1 port connected to the trunk line through which the clock source is synchronized to the peer device.
2. For V100R001C20 and V200R003, you can configure the clock source using the web management system.
(1) Choose System > Clock Source Configuration.
(2) Select Peer device from the Select clock source drop-down list box.
(3) Click Data Save in the upper right corner of the web management page.
Note: If the local device provides the clock source, you do not need to configure the clock source. If the peer device provides the clock source, you need to configure it.
A clock source allows the time of the U1900 to be synchronized from the upper-level device (that is, the peer device). This prevents frame slip (voice packet loss). If the U1900 connects to multiple devices through E1/T1 trunks, configure the clock source on any of these devices. The U1900 will synchronize time with this device. If the U1900 provides the clock source, you do not need to configure the clock source.