Aastra 9000i Series Administrator's Manual page 231

SIP Precedence Example
The following example shows the SIP proxy feature and example schema for storage and
parsing of the SIP configuration parameters.
The following SIP configuration is assumed:
# SIP network block
sip proxy ip:
sip proxy port: 5060
sip registrar ip:
sip registrar port: 4020
sip line3 proxy ip: siparator.vonage.com
sip line3 proxy port: 0
Line3 specifies per-line values for proxy IP address and proxy port, so the phone uses those
parameter values for SIP calls made on that line. However, because those parameters are part of
the SIP network block, the phone does not apply any of the global SIP network block
parameters. So even though the global parameters configure a SIP registrar, Line3 on the phone
ignores all global network block parameters. Since line3 does not contain a per-line SIP registrar
entry, the phone does not use a registrar for that line.
Backup Proxy/Registrar Support
The IP phones support a backup SIP proxy and backup SIP registrar feature. If the primary
server is unavailable, the phone automatically switches to the backup server allowing the user's
phone to remain in service.
How it Works
All SIP registration messages are sent to the primary registrar first. If the server is unavailable,
then a new registration request is sent to the backup registrar. This also applies to registration
renewal messages, which try the primary server before the backup.
Similarly, any outgoing calls attempt to use the primary proxy first, then the backup if necessary.
In addition, subscriptions for BLF, BLA, and explicit MWI can also use the backup proxy when
the primary fails. Outgoing calls and the previously mentioned subscriptions behave the same as
registrations, where the primary proxy is tried before the backup.
You can configure the backup SIP proxy on a global or per-line basis via the configuration files
or the Aastra Web UI.
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10.30.11.154
10.44.122.37
Note: Global SIP parameters apply to all lines unless overridden by a
per-line configuration.
Per-line settings are configurable for lines 1 through 7.
41-001343-01 Rev 02, Release 3.2.2