H.323 Call Setup
PTCL Training & Development
1
H.323 Call Example…….
H.323 Gatekeeper
IP network
PSTN
phone
PSTN
H.323 Gateway
H.323 Gateway
phone
H.225 describes how audio, video, data and control information be
managed
In IP network in equipment having H.323
H.245 are control signaling which includes receiving & transmitting
capabilities
Logical channel signaling etc
H.323 Call Example…….
• Call Setup step-1:
Discovery and Registration
Gatekeeper Request
H.323 Gatekeeper
H.323 Gateway
Gatekeeper
Confirm/Reject
Who is my Gatekeeper
3
H.323 Call Example…….
• Call Setup step-2:
Discovery and Registration
Registration Request
H.323 Gatekeeper
H.323 Gateway
Registration Confirm/Reject
Associate 212 NXX XXXX
With IP Address 12.10.2.1
Okay!
4
H.323 Call Example…….
• Call Setup step-3:
Location Request
Location Confirmation
H.323 Gatekeeper
H.323 Gateway
Admission Request
Admission confirm/reject
Find where is 212 NXX XXXX
Can I call that IP address 12.10.2.3
Yes, IP is identified
This much XX bps is
may be used
5
H.323 Call Example…….
• Call Setup step-4:
H.323
Gateway
H.323
Gate
keeper
H.245 manages
OLC (open logical
channel) like:
Type of media, UDP
Port # etc
H.323
Gateway
Q.931 for basic call
setup protocol
Logical channels for Media Streams
6
H.323 Few Messages……..
Gatekeeper Discovery
Location Request
Gatekeeper Discovery Request (GRQ)
Location Request (LRQ)
Gatekeeper Confirmation (GCF)
Location Confirmation (LCF)
Gatekeeper Rejection (GRJ)
Location Rejection (LRJ)
Bandwidth Change
Status Queries
Bandwidth Change Request (BRQ)
Info Request (IRQ)
Bandwidth Change Confirmation (BCF)
Info Request Response (IRR)
Bandwidth Change Rejection (BRJ)
Info Request Nak ((INAK)
Terminal/Gateway Registration
Call Admission
Registration Request (RRQ)
Admission Request (ARQ)
Registration Confirmation (RCF)
Admission Confirmation (ACF)
Registration Rejection (RRJ)
Admission Rejection (ARJ)
7
H.323 (H.225 Call Signaling)
• H.225:
– RAS (registration, admission & status)
channel is used to carry messages
used in the GateKeeper discovery
– Endpoint terminal registration
– Associates end-terminal address with
its call signaling transport address
• H.225:
--
Also describes how audio, video and control
information be managed in IP based n/w
8
H.323 (H.245 Control Signaling)
• H.245:
– Receiving & transmitting
capabilities
– Defines procedures for managing
logical channels
– Specifies as Open Logical Channel
structure like:
– Type of media and format (audio,
video codexs)
– Transport address Port numbers
– Direction of flow which port will
receive info
– May identify combinations of
channels audio, video
9
H.323 Call Stages
•
Discovery & Registration:
am I
Identify/Who
– RAS
•
•
•
•
•
Call Setup:
Who I want to
call
– RAS/H.225/Q.931
Call Negotiation:
Our
capabilities
– H.245
Media Channel Setup: Let’s open an audio
channel
– H.245
Media Transport:
Send the audio
– RTP/RTCP
Call Termination:
We are done
– H.245/H.225/Q.931/RAS
10