Yealink SIP-T54S Administrator's Manual page 280

Administrator's Guide for SIP-T2 Series/T19(P) E2/T4 Series/T5 Series/CP860/CP920 IP Phones
Select the desired value from the pull-down list of NTP by DHCP Priority.
2.
Click Confirm to accept the change.
3.
To configure the NTP server, time zone via web user interface:
Click on Settings->Time & Date.
1.
Select Disabled from the pull-down list of Manual Time.
2.
Select the desired time zone from the pull-down list of Time Zone.
3.
Select the desired location from the pull-down list of Location.
4.
Enter the domain name or IP address in the Primary Server and Secondary Server field
5.
respectively.
Enter the desired time interval in the Update Interval (15~86400s) field.
6.
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