Configuring SIP

The Session Initiation Protocol (SIP) is a generalized protocol for communication between endpoints involved in Internet services such as telephony, fax, video conferencing, instant messaging, and file exchange. The supported standard is described in RFC 3261, SIP: Session Initiation Protocol, which includes stateful firewall and Network Address Translation (NAT) support for SIP dialogs and UDP IPv4 transport of SIP messages.

To implement SIP on adaptive services interfaces, you configure the application-protocol statement at the [edit applications application application-name] hierarchy level with the value sip. For more information about this statement, see Configuring an Application Protocol. In addition, there are two other statements you can configure to modify how SIP is implemented:

• You can enable the router to accept any incoming SIP calls for the endpoint devices that are behind the NAT firewall. When a device behind the firewall registers with the proxy that is outside the firewall, the AS or MultiServices PIC maintains the registration state. When the learn-sip-register statement is enabled, the router can use this information to accept inbound calls. If this statement is not configured, no inbound calls are accepted; only the devices behind the firewall can call devices outside the firewall.

  To configure SIP registration, include the learn-sip-register statement at the [edit applications application application-name] hierarchy level:

  learn-sip-register;

  You can also manually inspect the SIP register by issuing the show services stateful-firewall sip-register command; for more information, see the JUNOS System Basics and Services Command Reference.

• You can specify a timeout period for the duration of SIP calls that are placed on hold. When a call is put on hold, there is no activity and flows might time out after the configured inactivity-timeout period expires, resulting in call state teardown. To avoid this, when a call is put on hold, the flow timer is reset to the sip-call-hold-timeout cycle to preserve the call state and flows for longer than the inactivity-timeout period.

  To configure a timeout period, include the sip-call-hold-timeout statement at the [edit applications application application-name] hierarchy level:

  sip-call-hold-timeout seconds;

  The default value is 7200 seconds and the range is from 0 through 36,000 seconds (10 hours).