Yealink SIP-T2 SERIES Administrator's Manual page 804

Administrator's Guide for SIP-T2 Series/T19(P) E2/T4 Series/CP860 IP Phones
Parameters
A tone is comprised of at most two different frequencies.
For SIP VP-T49G/SIP-T48G/T46G/T42G/T41P/T29G/T27P/CP860:
A tone is comprised of at most four different frequencies.
Duration: the duration (in milliseconds) of the dial tone, ranges from 0 to 30000ms.
You can configure at most eight different tones for one condition, and separate them
by commas. (e.g., 250/200,0/1000,200+300/500,200+500+800+1500/1000).
If you want the IP phone to play tones once, add an exclamation mark ―!‖ before
tones (e.g., !250/200,0/1000,200+300/500,200+500+800+1500/1000).
Note: It works only if the value of the parameter ―voice.tone.country‖ is set to
Custom.
Web User Interface:
Settings->Tones->Dial
Phone User Interface:
None
voice.tone.ring
Description:
Customizes the ringback tone.
The value format is Freq/Duration. For more information on the value format, refer to
the parameter ―voice.tone.dial‖.
Note: It works only if the value of the parameter ―voice.tone.country‖ is set to
Custom.
Web User Interface:
Settings->Tones->Ring Back
Phone User Interface:
None
voice.tone.busy
Description:
Customizes the tone when the callee is busy.
The value format is Freq/Duration. For more information on the value format, refer to
the parameter ―voice.tone.dial‖.
Note: It works only if the value of the parameter ―voice.tone.country‖ is set to
Custom.
Web User Interface:
Settings->Tones->Busy
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Permitted Values
String
String
Default
Blank
Blank