Yealink SIP-T2 SERIES Administrator's Manual page 346

Administrator's Guide for SIP-T2 Series/T19(P) E2/T4 Series/CP860 IP Phones
Account->Basic->Send Anonymous Code
Phone User Interface:
Menu->Features->Anonymous Call->Send Anony Code
account.X.anonymous_call_oncode
Description:
Configures the anonymous call on code to activate the server-side anonymous call
feature for account X.
X ranges from 1 to 16 (for SIP VP-T49G/SIP-T48G/T46G/T29G)
X ranges from 1 to 12 (for SIP-T42G)
X ranges from 1 to 6 (for SIP-T41P/T27P)
X ranges from 1 to 3 (for SIP-T40P/T23P/T23G)
X ranges from 1 to 2 (for SIP-T21(P) E2)
X is equal to 1 (for SIP-T19(P) E2/CP860)
Example:
account.1.anonymous_call_oncode = *72
Note: It works only if the value of the parameter ―account.X.send_anonymous_code‖
is set to 1 (On Code).
Web User Interface:
Account->Basic->Send Anonymous Code->On Code
Phone User Interface:
Menu->Features->Anonymous Call->On Code
account.X.anonymous_call_offcode
Description:
Configures the anonymous call off code to deactivate the server-side anonymous
call feature for account X.
X ranges from 1 to 16 (for SIP VP-T49G/SIP-T48G/T46G/T29G)
X ranges from 1 to 12 (for SIP-T42G)
X ranges from 1 to 6 (for SIP-T41P/T27P)
X ranges from 1 to 3 (for SIP-T40P/T23P/T23G)
X ranges from 1 to 2 (for SIP-T21(P) E2)
X is equal to 1 (for SIP-T19(P) E2/CP860)
Example:
account.1.anonymous_call_offcode = *73
324
Parameters Permitted Values
String within 32 characters
String within 32 characters
Default
Blank
Blank