Early Media
For call that require the IWF, the Oracle® Enterprise Session Border Controller supports a cut-through for early media for calls that originate in SIP or H.323.
For a session originating in SIP, the provisional message will contain the SDP information if a Fast Start OLC was received in the Call Proceeding, Alerting, or Progress messages. The same SDP will be sent in the SIP 200 OK.
For a session that starts in H.323, the Oracle® Enterprise Session Border Controller translates the SDP it receives in SIP messages (either a 180 or a 183) into the appropriate H.323 Fast Start elements: Alerting or Progress. If the Alerting or Progress messages contain Fast Start elements, the Progress Indicator Q.931 information element (IE) will also be included in the message with Progress Descriptor 8, indicating that in-band information or an appropriate pattern is now available. This causes the call party to enable end-to-end early media in the reverse direction in accordance with H.323 v4.
In addition, the Oracle® Enterprise Session Border Controller allows early media to flow in the forward direction for a call that requires the IWF starting in H.323 that is being translated to SIP. This happens after the Oracle® Enterprise Session Border Controller has received provisional response with SDP and has sent Alerting or Progress message with Fast Start to the calling party. Similarly, early media in the forward direction is enabled for a call that requires the IWF starting in SIP and being translated to H.323. This happens after the Oracle® Enterprise Session Border Controller received Alerting or Progress messages with Fast Start and maps the Alerting or Progress to SIP 180 or 183 provisional response with the SDP answer.