Aastra Telecom 41-001343-02 SIP Outbound Support, Backup Outbound Proxy and Failover Support

Global SIP Settings

SIP Outbound Support

The IP Phones support draft-ietf-sip-outbound-15. That specification describes how a SIP User Agent (UA) behind a fire- wall, reuses an existing connection (usually the REGISTER outbound connection) for the inbound request if the proxy sup- ports it. The UA uses keep-alive packets to monitor the connection status.

An Administrator can enable or disable this feature using the following parameter in the configuration files:

•sip outbound support

Note:

If the Global SIP parameter “Persistent TLS” is set on the phone, then only one TLS persistent connection can be estab- lished since the phone uses the local port 5061 for connection. If the Global SIP parameter “TLS” is set on the phone, more than one connection can be setup since the phone uses a random local port for connection.

Enabling/Disabling SIP Outbound Draft 15 Support

Use the following procedure to enable/disable SIP outbound Draft 15 support.

Configuration Files

For the specific parameter you can set in the configuration files, see Appendix A, the section, “SIP Outbound Support” on page A-60.

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 configura- tion scenarios, and the method by which this specific feature works in each scenario.

IF	THEN
SIP Outbound Disabled and
backup proxy and backup registrar	• All invite, register, and subscribe requests attempt to use the primary proxy/registrar
configured,	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 cur-
	rently 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.
backup proxy, backup registrar, and backup outbound	• All invite, register, and subscribe requests attempt to use the primary proxy/registrar
proxy configured,	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.
backup outbound proxy configured only,	• 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.

41-001343-02 REV04 – 05.2014 4-59