Managing The Time/Date; Daylight Saving Time - Linksys 900 Series Administrator's Manual

Chapter 3 Managing Linksys 900 Series IP Phones

Managing the Time/Date

The 900 Series phone obtains the current time information in one of the following ways:
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The time served by the NTP Server and the SIP Date Header are expressed in GMT time. The
local time is obtained by offsetting the GMT according to the time zone of the region. The
<Time Zone> parameter can be configured from the web page or through provisioning. This
time can be further offset using the <Time Offset (HH/mm)> parameter, which must be entered
in 24-hour format. This parameter can also be configured from the LCD display. The <Time
Zone> and <Time Offset (HH/mm)> offset values are not applied to the manual time/date
setup.

Daylight Saving Time

The 900 Series phone supports auto adjustment for daylight saving time. To enable this feature,
the administrator must configure the <Daylight Saving Time Rule> parameter on the Regional
tab. This parameter is a rule with three fields separated by semicolon (;) as shown below:
start=<start-time>;end=<end-time>;save=<save-time>
Where:
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<start-time> and <end-time> specify the start and end time and date of daylight saving time
and <save-time> is the amount of hour/min/sec to add to the current time during daylight
saving period.
The <save-time> value can be preceded by a negative (-) sign if subtraction is desired instead
of addition. If <weekday> is 0, it means the date to start or end daylight saving is at exactly the
given date. In that case, the <day> value must not be negative. If <weekday> is not zero, then
Document Version 3.1
NTP Server—One or two NTP servers can be configured to the phone. When it first boots up, the
phone tries to contact the NTP server to get the current time. Then the phone periodically
synchronizes the current time with the NTP server. The synchronization period is fixed at 1 hour. In
between the update, the phone tracks the time with its own internal clock.
SIP Messages—Each SIP message (request or response) sent to the SPA may contain a Date header
with the current time information. If the header is present, the SPA uses it to update its current time.
Manual Setup—900 Series phone also lets the user manually enter the current time and date from
the phone GUI or from the web page. However, this value is overridden by the NTP time or SIP
Message Date whenever they are presented to the phone. Manual setup requires the user to enter the
time in 24 hour format only.
<start-time> and <end-time> are of the form: <month>/<day>/<weekday>[/HH:[mm[:ss]]]
<save-time> is of form: [/[+|-]HH:[mm[:ss]]]
<month> = 1,2,12 (for Jan, Feb, Dec)
<day> = [+|-]1,2,3,...,,31
<weekday> = 1, 2, 3,..., 7 (for Mon, Tue, ..., Sun), or 0 which has special meaning
HH = hour (0-23)
mm = minute (0-59)
ss = second (0-59)
Linksys 900 Series IP Phone Administrator Guide
System Administration
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