Yealink SIP-T54S Administrator's Manual page 439

If it is set to 1 (On), the IP phone will reject incoming calls on all accounts.
Note: It works only if the value of the parameter "features.dnd.allow" is set to 1 (Enabled)
(except CP860 IP phones) and value of the parameter "features.dnd_mode" is set to 0
(Phone) (except SIP-T19(P) E2/CP860/CP920 IP phones).
Web User Interface:
Features->Forward&DND->DND->DND Status
Phone User Interface:
Menu->Features->DND->DND Status
features.dnd.on_code
Description:
Configures the DND on code to activate the server-side DND feature.
The IP phone will send the DND on code to the server when you activate DND feature on
the IP phone.
Example:
features.dnd.on_code = *71
Note: It works only if the value of the parameter "features.dnd.allow" is set to 1 (Enabled)
(except CP860 IP phones) and value of the parameter "features.dnd_mode" is set to 0
(Phone) (except SIP-T19(P) E2/CP860/CP920 IP phones).
Web User Interface:
Features->Forward&DND->DND->On Code
Phone User Interface:
Menu->Features->DND->On Code
features.dnd.off_code
Description:
Configures the DND off code to deactivate the server-side DND feature.
The IP phone will send the DND off code to the server when you deactivate DND feature on
the IP phone.
Example:
features.dnd.off_code = *72
Note: It works only if the value of the parameter "features.dnd.allow" is set to 1 (Enabled)
(except CP860 IP phones) and value of the parameter "features.dnd_mode" is set to 0
(Phone) (except SIP-T19(P) E2/CP860/CP920 IP phones).
Web User Interface:
Features->Forward&DND->DND->Off Code
Phone User Interface:
Configuring Basic Features
String within 32
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String within 32
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