Yealink SIP-T4X Administrator's Manual page 66

Administrator's Guide for SIP-T4X IP Phones
Mark the DST By Date radio box in the Fixed Type field.
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Enter the start time in the Start Date field.
Enter the end time in the End Date field.
Mark the DST By Week radio box in the Fixed Type field.
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Select the desired values from the pull-down lists of DST Start Month, DST Start
Day of Week, DST Start Day of Week Last in Month, DST Stop Month, DST Stop
Day of Week and DST Stop Day of Week Last in Month.
Enter the desired time in the Start Hour of Day field.
Enter the desired time in the End Hour of Day field.
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