Cisco ATA188-I2-A Administration Guide - Page 214

H.323 Signaling Scenarios Appendix D H.323 Signaling Table D-3 Action Descriptions Step Action Description 1. Local Admission Request (ARQ)-Local H.323 Cisco ATA sends a local ARQ message to the H.323 endpoint to H.323 gatekeeper gatekeeper seeking authorization to place a call over the H.323 network. 2. Local Admission Confirm (ACF) or Admission H.323 gatekeeper returns a ACF or ARJ message, indicating Reject (ARJ)-H.323 gatekeeper to the local H.323 whether or not the responding gatekeeper is going to allow endpoint the Cisco ATA device access to the network. 3. Open TCP Channel for Q.931 messaging TCP port 1720 is opened, making way for the forward and reverse flow of Q.931 signaling messages between the H.323 endpoints. 4. Q.931 Call Setup-Local H.323 endpoint to remote Call setup initiates from the local H.323 endpoint. H.323 endpoint 5. Q.931 Call Proceeding-Remote H.323 endpoint to Remote H.323 endpoint acknowledges call setup initiation. local H.323 endpoint 6. Remote Admission Request (ARQ)-Remote Cisco ATA to H.323 gatekeeper (Somewhat simultaneous, chronologically, to call setup and call proceeding) remote H.323 endpoint contacts the common H.323 gatekeeper, seeking authorization to complete the two-way H.323 network call. 7. Remote Admission Confirm (ACF) or Admission H.323 gatekeeper returns a ACF or ARJ message, indicating Reject (ARJ)-H.323 gatekeeper to the remote whether or not the responding gatekeeper is going to allow Cisco ATA the Cisco ATA device access to the network. 8. Q.931 Alerting-Remote H.323 endpoint to local Status message is sent to calling H.323 endpoint advising that H.323 endpoint the called party has been notified (phone ringing). 9. Q.931 Connect-Remote H.323 endpoint to local Status message is sent to calling H.323 endpoint advising that H.323 endpoint the called party has answered the call (phone off hook). 10. Open TCP Channel for H.245 Dynamically assigned TCP port is opened on both the local and remote H.323 endpoints, allowing for subsequent call setup activities (transmission and reception capability exchange, master-slave relationship determination, and so on). 11. H.245 Terminal Capabilities 12. H.245 Terminal Capabilities 13. H.245 Terminal Capabilities 14. H.245 Terminal Capabilities Various endpoint transmission and reception capabilities defining operation of voice, video, and data are exchanged and acknowledged to ensure consistent, reliable two-way communication between endpoints. 15. Exchange of Master-Slave Determination Determines master and slave assignments between H.323 Messages-Remote H.323 endpoint to local H.323 endpoints. endpoint 16. H.245 Open Audio Logical Channel-Local H.323 Before actual transmission or reception of voice, video, or endpoint to remote H.323 endpoint data, notification that the primary logical channel for the local H.323 endpoint has been opened, ensuring clear two-way communication. 17. H.245 Open Audio Logical Channel Remote H.323 endpoint acknowledges readiness. Acknowledgement-Remote H.323 endpoint to local H.323 endpoint Cisco ATA 186 and Cisco ATA 188 Analog Telephone Adaptor Administrator's Guide for H.323 (version 3.0) D-6 OL-4804-01