Yealink SIP-T48G Administrator's Manual page 261

Configuring Basic Features
Parameters Permitted Values Default
X ranges from 1 to 2 (for SIP-T21(P) E2)
For programable keys:
X=1-10, 12-14 (for SIP-T48G/T46G)
X=1-10, 13 (for SIP-T42G/T41P)
X=1-14 (for SIP-T29G/T27P)
X=1-10, 14 (for SIP-T23P/T23G/T21(P) E2)
Example:
linekey.1.type = 23
Default:
For SIP-T48G IP phones:
The default value of the line key 1-16 is 15, and the default value of the line key 17-29
is 0.
For SIP-T46G/T29G IP phones:
The default value of the line key 1-16 is 15, and the default value of the line key 17-27
is 0.
For SIP-T42G IP phones:
The default value of the line key 1-12 is 15, and the default value of the line key 13-15
is 0.
For SIP-T41P IP phones:
The default value of the line key 1-6 is 15, and the default value of the line key 7-15 is
0.
For SIP-T27P IP phones:
The default value of the line key 1-6 is 15, and the default value of the line key 7-21 is
0.
For SIP-T23P/T23G/T21(P) E2 IP phones:
The default value is 15.
For programable keys:
For SIP-T48G/T46G IP phones:
When X=1, the default value is 28 (History).
When X=2, the default value is 61 (Directory).
When X=3, the default value is 5 (DND).
When X=4, the default value is 30 (Menu).
When X=5, the default value is 28 (History).
When X=6, the default value is 61 (Directory).
When X=7, the default value is 51 (Switch Account Up).
When X=8, the default value is 52 (Switch Account Down).
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