Yealink SIP-T54S Administrator's Manual page 785

Configuring Advanced Features
Parameters Permitted Values Default
Configures the time interval (in seconds) for the IP phone to detect whether the working
outbound proxy server is available by sending the registration request after the fallback
server takes over call control.
X ranges from 1 to 16 (for SIP-T54S/T48G/T48S/T46G/T46S/T29G)
X ranges from 1 to 12 (for SIP-T52S/T42G/T42S)
X ranges from 1 to 6 (for SIP-T41P/T41S/T27P/T27G)
X ranges from 1 to 3 (for SIP-T40P/T40G/T23P/T23G)
X ranges from 1 to 2 (for SIP-T21(P) E2)
X is equal to 1 (for SIP-T19(P) E2/CP860/CP920)
Example:
account.1.outbound_proxy_fallback_interval = 3600
Note: It is only applicable to outbound proxy servers.
Web User Interface:
Account->Register->Proxy Fallback Interval
Phone User Interface:
Menu->Advanced (default password: admin) ->Accounts->Proxy Fallback Interval
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 failback mode for the IP phone to retry the primary server in failover for
account X.
0-newRequests: all requests are sent to the primary server first, regardless of the last server
that was used. If the primary server does not respond correctly, the IP phone will try to send
requests to the secondary server.
1-DNSTTL: the IP phone will send requests to the last registered server first. If the TTL for
the DNS A records on the registered server expires, the phone will retry to send requests to
the primary server.
2-Registration: the IP phone will send requests to the last registered server first. If the
registration expires, the phone will retry to send requests to the primary server.
3-duration: the IP phone will send requests to the last registered server first. If the time
defined by the parameter "account.X.sip_server.Y.failback_timeout" expires, the phone will
retry to send requests to the primary server.
X ranges from 1 to 16 (for SIP-T54S/T48G/T48S/T46G/T46S/T29G)
X ranges from 1 to 12 (for SIP-T52S/T42G/T42S)
X ranges from 1 to 6 (for SIP-T41P/T41S/T27P/T27G)
X ranges from 1 to 3 (for SIP-T40P/T40G/T23P/T23G)
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