Yealink SIP-T48G Administrator's Manual page 405

Configuring Advanced Features
Parameters Permitted Values Default
X ranges from 1 to 16 (for 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-T23P/G).
X ranges from 1 to 2 (for SIP-T21(P) E2).
Web User Interface:
None
Phone User Interface:
None
Integer from 10
account.X.fallback.timeout 120
to 2147483647
Description:
Configures the time interval (in seconds) for the IP phone to detect whether the
working server is available by sending the registration request after the fallback
server takes over call control.
It is only applicable to the Successive Registration mode.
X ranges from 1 to 16 (for 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-T23P/G).
X ranges from 1 to 2 (for SIP-T21(P) E2).
Web User Interface:
None
Phone User Interface:
None
account.X.sip_server.Y.failback_mode
0, 1, 2 or 3 0
(X ranges from 1 to 16, Y ranges from 1 to 2)
Description:
Configures the way in which the phone fails back to the primary server for call
control in the failover mode.
0-newRequests: all requests are sent to the primary server first, regardless of the last
server that was used.
1-DNSTTL: the IP phone will send requests to the last registered server first. If the time
defined by DNSTTL on the registered server expires, the phone will retry to send
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