Date Customization Rule; Call Display - Yealink T5 Series Administrator's Manual

Administrator's Guide for SIP-T58V/T58A/T56A/CP960 IP Phones
"YYYY" represents a four-digit year, and "YY" represents a two-digit year.
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Web UI Settings->Time&Date->Date Format
Phone UI Settings->Basic Settings->Time&Date->Time & Date Format->Date Format

Date Customization Rule

You need to know the following rules when customizing date formats:
Format
Y/YY
Y is used more than twice (for example, YYY, YYYY)
M/MM
MMM
M is used more than three times (for example, MMMM)
D is used once or more than once (for example, DD)
W/WW
W is used more than twice (for example, WWW,
WWWW)

Call Display

By default, the phones present the contact information (including avatar and identity) when receiving an incoming
call, dialing an outgoing call or engaging in a call.
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Description
It represents a two-digit year.
For example, 16, 17, 18...
It represents a four-digit year.
For example, 2016, 2017, 2018...
It represents a two-digit month.
For example, 01, 02,..., 12
It represents the abbreviation of the month.
For example, Jan, Feb,..., Dec
It represents the long format of the month.
For example, January, February,..., December
It represents a two-digit day.
For example, 01, 02,..., 31
It represents the abbreviation of the day of week.
For example, Mon, Tue,..., Sun
It represents the long format of the day of week.
For example, Monday, Tuesday,..., Sunday