Cisco ATA186-I2 Administrator's Manual page 214

H.323 Signaling Scenarios
Table D-3 Action Descriptions
Step Action
1. Local Admission Request (ARQ)—Local H.323
endpoint to H.323 gatekeeper
Local Admission Confirm (ACF) or Admission
2.
Reject (ARJ)—H.323 gatekeeper to the local H.323
endpoint
Open TCP Channel for Q.931 messaging
3.
Q.931 Call Setup—Local H.323 endpoint to remote
4.
H.323 endpoint
Q.931 Call Proceeding—Remote H.323 endpoint to
5.
local H.323 endpoint
Remote Admission Request (ARQ)—Remote
6.
Cisco ATA to H.323 gatekeeper
Remote Admission Confirm (ACF) or Admission
7.
Reject (ARJ)—H.323 gatekeeper to the remote
Cisco ATA
Q.931 Alerting—Remote H.323 endpoint to local
8.
H.323 endpoint
Q.931 Connect—Remote H.323 endpoint to local
9.
H.323 endpoint
Open TCP Channel for H.245
10.
11. H.245 Terminal Capabilities
H.245 Terminal Capabilities
12.
H.245 Terminal Capabilities
13.
H.245 Terminal Capabilities
14.
15. Exchange of Master-Slave Determination
Messages—Remote H.323 endpoint to local H.323
endpoint
16. H.245 Open Audio Logical Channel—Local H.323
endpoint to remote H.323 endpoint
H.245 Open Audio Logical Channel
17.
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
Description
Cisco ATA sends a local ARQ message to the H.323
gatekeeper seeking authorization to place a call over the
H.323 network.
H.323 gatekeeper returns a ACF or ARJ message, indicating
whether or not the responding gatekeeper is going to allow
the Cisco ATA device access to the network.
TCP port 1720 is opened, making way for the forward and
reverse flow of Q.931 signaling messages between the H.323
endpoints.
Call setup initiates from the local H.323 endpoint.
Remote H.323 endpoint acknowledges call setup initiation.
(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.
H.323 gatekeeper returns a ACF or ARJ message, indicating
whether or not the responding gatekeeper is going to allow
the Cisco ATA device access to the network.
Status message is sent to calling H.323 endpoint advising that
the called party has been notified (phone ringing).
Status message is sent to calling H.323 endpoint advising that
the called party has answered the call (phone off hook).
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).
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.
Determines master and slave assignments between H.323
endpoints.
Before actual transmission or reception of voice, video, or
data, notification that the primary logical channel for the
local H.323 endpoint has been opened, ensuring clear
two-way communication.
Remote H.323 endpoint acknowledges readiness.
Appendix D H.323 Signaling
OL-4804-01