Aastra 9000i Series Administrator's Manual page 233

Backup Outbound Proxy and Failover Support
The IP phones support a backup outbound proxy and failover. This feature provides the
following:
• The ability to specify a backup outbound proxy.
• The ability to support SIP outbound on all connection types.
• The ability to configure the SIP outbound keep alive timer.
• The ability to reestablish failed outbound connections in the background.
• The ability to support the DNS Cache Time-to-Live (TTL) requirements
Using this feature depends on the SIP network settings on your phone. The following table
identifies network configuration scenarios, and the method by which this specific feature works
in each scenario.
IF
SIP Outbound Disabled and
backup proxy and backup registrar
configured,
backup proxy, backup registrar, and
backup outbound proxy configured,
backup outbound proxy configured only,
4-70
THEN
• All invite, register, and subscribe requests attempt to use the
primary proxy/registrar first
• If the primary registrar fails, the phone registers to the backup
proxy.
• If the backup proxy fails, the phone registers using the Address of
Record (AOR) of the backup proxy, and moves all subscriptions to
the backup proxy.
• When the primary registrar comes back online, the phone registers
to it using the currently active AOR.
• When the primary proxy comes back online the phone registers
with the primary AOR to the currently active registrar and moves
all subscriptions to the primary proxy.
• All invite, register, and subscribe requests attempt to use the
primary proxy/registrar first.
• If any connection fails, the phone registers the backup AOR on the
backup registrar. It moves all subscriptions to the backup proxy.
• When the primary is functional again, registration and
subscriptions are moved back to the primary proxy/registrar.
• All invite, register and subscribe requests are sent through the
primary outbound proxy first.
• If the primary proxy fails, the phone performs registration and
subscriptions through the backup outbound proxy.
• When the primary proxy comes back online, the registrations and
subscriptions are performed again through the primary outbound
proxy.
41-001343-01 Rev 02, Release 3.2.2