Basic Call

In the following sample basic call, IP PBX A sends an H.323 Slow Starts message ultimately destined for the PSTN through the Oracle® Enterprise Session Border Controller . The Oracle® Enterprise Session Border Controller performs translation to SIP and inserts default information about media. Once the PSTN gateway responds with a 183 containing SDP, the Oracle® Enterprise Session Border Controller sends that information to IP PBX A. Then the Oracle® Enterprise Session Border Controller and the IP PBX exchange TCS- and OLC-related messages, and they negotiate master-slave determination. The Oracle® Enterprise Session Border Controller also sends IP PBX A a Call Progress message with a progress indicator of 8.

After the ringback tone, the proxy sends a 200 OK message with SDP to the system. The Oracle® Enterprise Session Border Controller sends a Connect message to the IP PBX A, and then it sends another SIP INVITE to the proxy that contains amended SDP (if that information about media is different from the default). After 200 OK and ACK messages are exchanged, media (RTP/RTCP) flow takes place.