Yealink SIP-T48G Administrator's Manual page 264

Administrator's Guide for SIP-T2_Series_T4_Series IP Phones
1 to 2 (for SIP-T21(P) E2)
1-Line 1
2-Line 2
...
16-Line 16
Example:
linekey.1.line = 1
Web User Interface:
DSSKey->Line Key/ Programable Key->Line
Phone User Interface:
Menu->Features->DSS Keys->Line Key X->Account ID
linekey.X.value/ programablekey.X.value
Description:
Configures the group call pickup feature code.
For line keys:
X ranges from 1 to 29 (for SIP-T48G).
X ranges from 1 to 27 (for SIP-T46G/T29G).
X ranges from 1 to 15 (for SIP-T42G/T41P).
X ranges from 1 to 21 (for SIP-T27P).
X ranges from 1 to 3 (for SIP-T23P/G)
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.value = *98
Web User Interface:
DSSKey->Line Key/ Programable Key->Value
Phone User Interface:
Menu->Features->DSS Keys->Line Key X->Value
250
Parameters Permitted Values
String within 99
characters
Default
Blank