When you assign the Speed Dial to the line key, this parameter is used to specify
the number you want to dial out.
linekey.1.value = 1001
(Optional.) Configures the label displaying on the LCD screen for each line key
and each soft key.
This is an optional configuration.
For line keys (not applicable to SIP-T19(P) E2 IP phones and CIP860 IP phones):
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-T40P/T23P/T23G)
X ranges from 1 to 2 (for SIP-T21(P) E2)
For programable keys: