Cisco ATA188-I2-A Administration Guide - Page 223

Appendix D H.323 Signaling H.323 Signaling Scenarios Figure D-3 H.323 Call Setup from H.323 Network to Circuit Switched Network Endpoint 1 Gatekeeper Gateway to CSN/PSTN V V H.225 Admission Request (ARQ) H.225 Admission Confirm (ACF) Open TCP Channel for Q.931 Q.931 Call Setup Q.931 Call Processing H.225 Admission Request (ARQ) H.225 Admission Confirm (ACF) Q.931 Alerting Q.931 Connect Open TCP Channel for H.245 H.245 Terminal Capabilites H.245 Terminal Capabilites H.245 Terminal Capabilites H.245 Terminal Capabilites Exchange of Master-slave Determination Messages H.245 Open Audio Logical Channel H.245 Open Audio Logical Channel Acknowledgement H.245 Open Audio Logical Channel H.245 Open Audio Logical Channel Acknowledgement Bi-directional Audio with Transcoding Between Endpoint and Gateway 79600 Table D-5 Action Descriptions Step Action Description 1. Local Admission Request (ARQ)-Local endpoint to H.323 gatekeeper Cisco ATA sends a local ARQ message to the H.323 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 whether or not the responding gatekeeper is going to allow the endpoint 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 endpoint and the CSN/PSTN Gateway. 4. Q.931 Call Setup-Local H.323 endpoint to Call setup initiates from the local H.323 endpoint. remote H.323 endpoint 5. Q.931 Call Proceeding-Remote H.323 endpoint to local H.323 endpoint Gateway acknowledges call setup initiation. OL-4804-01 Cisco ATA 186 and Cisco ATA 188 Analog Telephone Adaptor Administrator's Guide for H.323 (version 3.0) D-15