Alcatel Temporis IP800 Administrator's Manual page 22

Use the left or right navigation keys to choose a preferred time format: 12 hour or 24
hour.
Use the left or right navigation keys to choose a preferred date format (7 kinds of date
formats are supported).
Press the Save soft key to save the changes and return to the previous screen.
To change the Time and Date via the Web interface:
Choose Phone->Preference. You can also change the Update Interval which specifies
the time frequency that the phone refreshes the time automatically. Please refer to the
instruction above for parameters' detail.
To change the Daylight Saving Time settings via the Phone interface:
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Temporis IP800 Administrator Guide Ed1.0