SIP Profile - Session Timer

The SIP Session Timer object allows the IMG 2020 to be able to refresh SIP sessions by either the Re-INVITE or Update method. During an active call, the Re-INVITE method allows the IMG 2020 to send repeated Re-INVITE messages to allow it to determine whether a SIP Session is active or not. The Update Method functions very similar to the Re-INVITE method except the update method is able to send an update message before the INVITE is actually sent. This allows the IMG 2020 to have an impact on the SIP Session before the INVITE message is sent. Early Media would be an example of the Update Method. See below for more specific information on these two methods. The Re-Invite and Update Methods are from RFC 4028 and RFC 3311

Web GUI Page

Dialogic > Profiles > SIP Profile (SGP) > New SIP Session Timer

Open

Maximum Objects

One SIP Session Timer object per SIP Profile (SGP) object.

Related Topics and Dependencies

The SIP Profile (SGP) must be created first. Once the SIP Profile (SGP) object is created, the SIP Session Timer object can be created under it. The SIP Profile (SGP) object can then be associated with an External Gateway object configured as a SIP gateway. The IMG 2020 would then communicate with the external gateway using the SIP Proxy.

SIP Session Timer Overview

SIP Session Timer Call Flows

IMG 1010 - Update Method 

Field Descriptions

Session Timer

Enable (Default) - Enable Session Timer object with related fields on the IMG 2020. The supported header in outgoing request will contain the tag timer and the IMG 2020 will always request a session timer.

Disable - Disable Session Timer object on the IMG 2020. The supported header in outgoing request will NOT contain the tag timer. If incoming request has a required header that contains the tag timer, the request will be rejected with a 420 - Bad Extension response code.

Clear Calls First on Session Expired

Enable - IMG 2020 clears calls right after session expired so that IMG 2020 releases the calls much faster when the external SIP gateway or application server is down. Otherwise, the system will normally go through the standard SIP call flow with respect to Session-Refresh (retries) or SIP BYE. 

Disable (Default) -  IMG needs to wait for the SIP session refresh re-transmits and also for the SIP BYE re-transmits to clear the calls following session expired.

Enforce Feature

Enable - If the Session Timer field above is enabled and the Enforce Feature field is enabled then the IMG 2020 will perform the session refresh request even if the remote gateway does not support session timer. The session timer cannot be turned off in mid dialog.

Disable (Default) - If the Session Timer field above is enabled and the Enforce Feature field is disabled then the IMG 2020 will NOT perform the session refresh request to a remote gateway that does not support session timer. If the Session Timer field above is disabled then the Enforce Feature field is disabled also.

Refresh Method

Re-Invite - If Re-Invite is selected, the IMG 2020 will use the Re-Invite method. If the remote gateway supports only the UPDATE Method, the IMG 2020 will use the Re-Invite method regardless.

Update - The Update is selected, the IMG 2020 will use the UPDATE Method only if the remote gateway supports the Update Method. If remote gateway does not support the Update Method and Update is selected then the IMG 2020 will default to the Re-invite Method.

Refresher

Only applicable for initial refresh response when IMG 2020 acts as UAS (User Agent Server) and the request does not specify refresher.

Local - The IMG 2020 will perform a refresh.

Remote - The IMG 2020 will wait for refresh request.

Minimum Session Expires

This field establishes the lower bound session refresh interval. It can be raised but cannot be lowered. It is mandatory on a 422 response and optional on INVITE and UPDATE request. To modify, highlight the seconds box and enter a different value.

• The Minimum Session Expires Timers Default = 150 seconds.

• The Minimum Session Expires Timers range is 90-86400 seconds.

Session Expire

This is the time at which an element will consider the session timed out, if no successful session refresh transaction occurs beforehand. The Session Expires field establishes the upper bound session refresh interval. The Session Expires parameter can be lowered but cannot be below the value specified in Minimum Session Expires Timer (Min-SE). The Session Expires parameter is optional on INVITE or UPDATE request and 2xx response to INVITE or UPDATE. To modify, highlight the seconds box and enter a different value.

• The Default value is 1800 seconds (30 minutes).

• The Session Expires Timers range is 90-86400 seconds.