RFC 4028 Session Timers

The Oracle® Enterprise Session Border Controller supports RFC 4028 Session Timers. In this role, it acts as a B2BUA between two endpoints and then enforces the timer values on each call leg independently. The RFC 4028 abstract states:

This document defines an extension to the Session Initiation Protocol (SIP). This extension allows for a periodic refresh of SIP sessions through a re-INVITE or UPDATE request. The refresh allows both user agents and proxies to determine whether the SIP session is still active. The extension defines two new header fields:

• Session-Expires—which conveys the lifetime of the session
• Min-SE—which conveys the minimum allowed value for the session timer

The following parameters in the session-timer-profile configuration element are used for this feature:

session-expires—The value of the session expires header in seconds

min-se—The value of the Min-SE header in seconds (this is a minimum session expires value)

force-reinvite—Sets if the Oracle® Enterprise Session Border Controller will send a reINVITE to refresh the session timer when applicable.

request-refresher—Set on the outbound side of a call what the Oracle® Enterprise Session Border Controller sets the refresher parameter to. Valid values are uac, uas, or none.

response-refresher—Set on the inbound side the value of the refresher parameter in the 200OK message. Valid values are uac or uas.

In this section, the notion that a UAC or UAS supports Session Timers is indicated by the presence of the Supported: timer header and option tag.