Cisco 7800 Series Administration Manual page 55

Specify a value for primary proxy (or primary outbound proxy) and alternate proxy (or alternate outbound
Note
proxy) for the feature to function properly.
Dual Registration and DNS SRV Limitations
• When Dual Registration is enabled, DNS SRV Proxy Fallback or Recovery must be disabled.
• Do not use Dual Registration along with other Fallback or Recovery mechanisms. For example: Broadsoft
mechanism.
• There is no recovery mechanism for feature request. However, the administrator can adjust the
reregistration time for a prompt update of the registration state for primary and alternate proxy.
Dual Registration and Alternate Proxy
When the Dual Register parameter is set to No, Alternate Proxy is ignored.
Failover and Recovery Registration
• Failover—The phone performs a failover when transport timeout/failure or TCP connection failures; if
Try Backup RSC and Retry Reg RSC values are datafilled.
• Recovery—The phone attempts to reregister with the primary proxy while registered or actively connected
to the secondary proxy.
Fallback Behavior
The fallback occurs when the current registration expires or Proxy Fallback Intvl fires.
If the Proxy Fallback Intvl is exceeded, all the new SIP messages go to primary proxy.
For example, when the value for Register Expires is 3600 seconds and Proxy Fallback Intvl is 600 seconds,
the fallback triggers 600 seconds later.
When the value for Register Expires is 800 seconds and Proxy Fallback Intvl is 1000 seconds, the fallback
triggers at 800 seconds.
After successful registration back to the primary server, all SIP messages go to the primary server.
RFC3261
The Cisco IP Phone supports RFC-3261, the SIP UPDATE Method.
SIP NOTIFY XML-Service
The Cisco IP Phone supports the SIP NOTIFY XML-Service event. On receipt of a SIP NOTIFY message
with an XML-Service event, the phone challenges the NOTIFY with a 401 response if the message does not
contain correct credentials. The client must furnish the correct credentials using MD5 digest with the SIP
account password for the corresponding line of the IP phone.
The body of the message can contain the XML event Message. For example:
<CiscoIPPhoneExecute>
Cisco IP Phone 7800 Series for Third-Party Call Control Administration Guide
SIP and NAT Configuration
41