Active Speaker Notification; Figure 10-4: Applying Media Services On A Conference -- Sip Call Flow - AudioCodes Mediant 1000 User Manual

SIP User's Manual

Figure 10-4: Applying Media Services on a Conference -- SIP Call Flow

10.1.2.5 Active Speaker Notification

After an advanced conference is established, the Application Server can subscribe to the
device to receive notifications of the current set of active speakers in a conference at any
given moment. This feature is referred to as Active Speaker Notification (ASN) and is
designed according to the MSCML standard. Notifications provide information on the
number of active participants and their details.
The notifications are sent unsolicited at specific intervals requested by the application and
only when a change in the number of active conference speakers occurs. If a change in the
speakers list occurs, the server issues an INVITE to the specific SIP UA, and then transfers
the call to the UA.
Event notifications are sent in SIP INFO messages, as shown in the example below of XML
Response Generated for ASN:
<?xml version="1.0" encoding="utf-8"?>
<MediaServerControl version="1.0">
<notification>
<conference uniqueID="3331" numtalkers="1">
<activetalkers>
<talker callID="9814266171512000193619@10.8.27.118"/>
</activetalkers>
</conference>
</notification>
</MediaServerControl>
Version 5.4 475
10. Media Server Capabilities
May 2008