Time synchronization
From Zenitel Wiki
Synchronizing using a NTP server
The AlphaCom can synchronize its real time clock with Network Time Protocol (NTP) time servers on the IP network. The syncronization is taking place once every hour. To activate the feature, define the IP address of a valid NTP server in the Time and Date settings in AlphaWeb.
If the AlphaCom is connected to the internet, you'll find a list of NTP servers here: http://support.microsoft.com/kb/262680
The NTP uses port 123 so this port must be opened on a firewall or router to ensure proper communication with the NTP server.
Synchronizing using GPS network
The AlphaCom can syncronize its real time clock with a Master Clock which receives its time from GPS (Global Positioning System) satelittes.
(Details to follow later..)