SIP - H.323 Call Flow & H.323 - SIP Flow

1.

SIP-to-H.323 Call Procedure in Fast-Start Mode.

http://localhost:7890/pages/31186402/01/31186402/01/resources/figure/fig_cn_80_02_0000105.png

pon receiving an INVITE message carrying SDP information from the SoftX3000, the SE2600 sends a Setup message carrying faststart information to the GK. The GK returns an Alerting or a Connect message carrying media information to the SE2600. The SE2600 then sends a 180 or 200 message carrying SDP information to the SoftX3000. Media negotiation is complete and a call is established in fast start mode.

2. H.323-to-SIP call procedure (in fast start mode)

http://localhost:7890/pages/31186402/01/31186402/01/resources/figure/fig_cn_80_02_0000106.png

Upon receiving a Setup message carrying faststart information from the GK, the SE2600 sends an INVITE message carrying SDP information to the SoftX3000. The SoftX3000 returns a 180 or 200 message carrying SDP information to the SE2600. The SE2600 then sends an Alerting or a Connect message carrying faststart information to the GK. Media negotiation is complete and a call is established in fast start mode.

Call Procedure in Normal Start Mode:

SIP-to-H.323 Call procedure (in normal start mode)

http://localhost:7890/pages/31186402/01/31186402/01/resources/figure/fig_cn_80_02_0000107.png

1. Upon receiving an INVITE message (carrying no SDP information) from the SoftX3000, the SE2600 sends a Setup message (carrying no SDP information) to the GK.
2. The GK sends a Connect message carrying an H.245 address. The SE2600 and the GK establish a TCP connection and use the TCS procedure to perform media negotiation.
3. After the GK and SE2600 exchange an OLC OLCAck message, the SE2600 sends a 200 message that carries SDP to the SoftX3000 for media negotiation.
4. Upon receiving an ACK response from the SoftX3000, the SE2600 completes media negotiation and establishes a call in normal start mode.
5. After the call is over, the SE2600 receives a BYE message from the SoftX3000. An ESC message is exchanged between the GK and the SE2600 to release the call. The SE2600 sends a ReleaseComplete message to the GK, and a 200 OK message to the SoftX3000.