This feature assists with originating sessions towards the Conference Factory by augmenting the REFER request sent from the UE to the Conference Factory .
The moderator UE sends a REFER request to add and remove conference participants. Such a REFER request contains a Refer-To header that is often re-written by Application Servers.
The original value as sent by the UE is necessary for Re-INVITE based conferencing. This can be achieved through two means:
-
copying the original value into a different header - the approach taken by this feature, or
-
disabling any Application Server invocation for originating attempts towards the Conference Factory - the approach taken prior to introduction of this feature when re-INVITE based conference is used.
Feature cheat sheet
| B2BUA Instance | SAS Support | Originating / Terminating | Point(s) in Session Plan | Network Operator Data | Subscriber Data | Stateful or Stateless | POJO or SBB Feature | Other notes |
|---|---|---|---|---|---|---|---|---|
SCC |
Yes |
Originating only |
`SubscriptionSipRequest` |
None |
None |
Stateless |
POJO |
Copies |
Statistics
SCCAugmentRefer statistics are tracked by the sentinel.volte.sip SBB and can be found under the following parameter set:
SLEE-Usage → [sentinel.volte.sip service name] → [sentinel.volte.sip SBB name] → feature.SCCAugmentRefer
| Statistic | Increments when… |
|---|---|
Started |
The feature is started. |
FailedToStart |
Sentinel VoLTE encounters an error while attempting to start the feature. |
IssuedWarning |
A non-fatal problem is encountered and the feature issues a warning. |
FailedDuringExecution |
A fatal problem is encountered and the feature cannot execute correctly. |
TimedOut |
The feature takes too long to complete and Sentinel VoLTE aborts execution. |
ReceivedRefer |
The feature is triggered on a REFER request. |
AugmentedRefer |
The REFER request contains a |
Behaviour
This feature ignores any Trigger that is not a SIP REFER request.
If the REFER request has a Refer-To header the feature copies the incoming Refer-To header into an outbound X-MSW-Original-Refer-To header.
This is to facilitate conference moderator Access Transfer where an originating SCC-AS must be present between the moderator UE and the call to the Conference Factory.
The rationale for this behaviour is that the Refer-To header tends to be re-written by routing B2BUA’s and the original value must be visible to the Conference Factory for re-INVITE based flows.
