1. Overview of H323 and H323-SIP Gateway Agenda Crash course on H323
How is SIP different ?
Problems in Interworking
Possible Solutions
Current Implementation/Status
Q/A
Demo
22-Jun-18
© 1999, Columbia University

2. What is H323 ? Q931 H245 RTP RAS H450 H323 Box H323 Network
Multimedia Communication Protocol
Terminal/
User Agent
Terminal/
User Agent
Gatekeeper
(Guardian)
Q931
H245
RTP
RAS
H450
MCU
(Meeting Hall)
Gateway
(Bridge to another
network)
H323 Box
H323 Network
22-Jun-18
© 1999, Columbia University

3. Terminal Control/Devices
What is H323 ?
Terminal Control/Devices
Q931
H245
RAS
RTCP
Codecs
RTP
TPKT
TCP
UDP
IP and lower layers
H323 Stack
22-Jun-18
© 1999, Columbia University

4. What is H323 ? H323 On Internet, Physical Configuration A B C
IP Router
IP Router
Guardian
User Agent
User Agent
Meeting Hall
User Agent B C
H323 On Internet,
Physical Configuration
22-Jun-18
© 1999, Columbia University

5. What is H323 ? Logical Configuration A Meeting Hall C B Guardian
User Agent
Meeting Hall
User Agent
User Agent C B
Logical Configuration
22-Jun-18
© 1999, Columbia University

6. H323 Operation Take permission from your guardian
Find the address of the person to call
Dial the number/Pick up the phone
Tell the other party what all languages you can speak/understand
Wait for him to tell you his capabilities
Tell him what language you are going to speak during the conversation
Start talking (and listening)
When you are done say Bye to other party
Hang up
Inform your guardian that you are done.
22-Jun-18
© 1999, Columbia University

7. H323 Operation
Take permission from your guardian ( RAS Admission Control)
Find the address of the person to call ( RAS Address resolution)
Dial the number (Q931 call setup)
Tell the other party what all languages you can speak/understand (H245 capability negotiation)
Wait for him to tell you his capabilities (H245 Capability negotiation)
Tell him what language you are going to speak during the conversation (H245 Logical channel signaling; languages=codecs)
Start talking (and listening) (Data transfer using RTP/RTCP)
When you are done say Bye to other party (H245 end session)
Hang up (Q931 call termination)
Inform your guardian that you are done. (RAS Admission Control)
22-Jun-18
© 1999, Columbia University

8. H323 Operation Some additional things are also required.
Search for your guardian (RAS Gatekeeper discovery)
You can operate without a guardian
You can use multiple languages to communication
You can switch language during your talk as long as you talk what the other guy understands, however you have to explicitly tell him that you are switching.
Saying Bye before hanging up is optional
And many more . . .
22-Jun-18
© 1999, Columbia University

9. + and -
+ It works
+ There are many existing implementation ... Some are free.
+ Supports lots of languages (codecs).
+ Interoperable with other other protocols H320 (ISDN), H324 (POTS).
- Too complicated (a) ASN (b) Huge
- Lots of protocols are combined together under the heading H Redundancy.
- Guardian is overloaded and Meeting hall is full !!
- Firewalls ? ...Difficult to develop.
22-Jun-18
© 1999, Columbia University

10. How is SIP different ? Text based ... No legacy from ISDN/POTS Mr. A
Mr. B, you are invited to talk to me. I can understand
English and German.
OK, But I can understand English and French only.
Let’s talk
Mr. A
Words... Mots... Words ... Words ...
Mr. B
Words... Words ... Wörter ... Words
22-Jun-18
© 1999, Columbia University

11. Big Picture (Voice communication)
SIP/IP
H323/IP
Cellular
PSTN
ISDN
22-Jun-18
© 1999, Columbia University

12. Big Picture (Inside) SIP/IP H323/IP Cellular ISDN PSTN Gateway Gateway
22-Jun-18
© 1999, Columbia University

13. H323-SIP Interworking User Registration H245 <=> SDP
Direct Data Traffic between SIP and H323
Transparent Support for Codecs
Call sequence mapping (next slide)
22-Jun-18
© 1999, Columbia University

14. H323-SIP Interworking H323 Network SIP Network Dial Mr X
Mr. B, you are invited to talk to me. I can understand
English and German.
Pickup...Connected
I speak/understand English andFrench.
OK, But I can understand English and French only.
Mr. A
Mr. X
Mr. B
I’ll speak English
Let’s talk
I’ll speak French
Words...
Words...
Words...
Words...
22-Jun-18
© 1999, Columbia University

15. H323-SIP Interworking H323 Network SIP Network Dial Mr A Mr. X Mr. B
Mr. A, you are invited to talk to me. I can understand
English and German.
Dial Mr A
Mr. X
Mr. B
Pickup...Connected
I speak/understand English andFrench.
Mr. A
I understand English andGerman.
OK, But I can understand English only.
I’ll speak English
I’ll speak English
Let’s talk
Words...
Words...
Words...
Words...
22-Jun-18
© 1999, Columbia University

16. H323-SIP Interworking H323 Network SIP Network Dial Mr B
Pickup...Connected
Mr. B, you are invited to talk to Mr A. He can understand
English only.
I speak/understand English (default).
Mr. A
Mr. X
Mr. B
I’ll speak English
OK, But I can understand English and French only.
I’ll speak English
Let’s talk
Words...
Words...
Words...
Words...
22-Jun-18
© 1999, Columbia University

17. H323-SIP Interworking H323 Network SIP Network Dial Mr B
Mr. B, you are invited to...English
Pickup...Connected
OK, ... English and French only.
I understand En and Fr.
Mr. A
Mr. X
Mr. B
I’ll speak English
I’ll speak English
Let’s talk
Words...
Words...
Words...
Words...
22-Jun-18
© 1999, Columbia University

18. H323-SIP Interworking
All these solutions have one or the other problem.
We Need Smart H323 Phone ...
Dial Mr B, Also I can speak English and can Understand English and German
Pickup..Connected, OK...I understand English and I’ll speak German.
H323 V2.0 Fast Connect
22-Jun-18
© 1999, Columbia University

19. H323-SIP Interworking H323 Network SIP Network Mr. A Mr. B Mr. X
Dial Mr B. Speak En
Understand En and Fr
Mr. B, you are invited to talk to Mr A. He speaks English and understands English and French
Pickup...Connected
Speak English and understand
English.
OK, ... I understand English and German.
Let’s talk. But Mr A
understands only English.
Mr. A
Mr. X
Mr. B
Words...
Words...
Words...
Words...
22-Jun-18
© 1999, Columbia University

20. Implementation Two way call. Either side can initiate the call
Fast Connect as well as non-Fast connect
RTP packets directly between the endpoints
Codecs supported ?
Multiple calls simultaneously - ?
User Registration - NO
Call transfer and Multiparty conference - NO
22-Jun-18
© 1999, Columbia University

21. Signaling GatewayApplication
Implementation
Signaling GatewayApplication
API
API
H323 Library
SIP Library
H323 Cloud
SIP Cloud
22-Jun-18
© 1999, Columbia University

22. Demonstration H323 SIP Signaling Gateway E-Phone (Embedded SIPPC PC
E-Phone
(Embedded SIP
user agent)
Windows ®
Netmeeting®
V3.0.1
LAN
Signaling Connection (Q931,H245,SIP,etc)
Data Connection (RTP/RTCP)
22-Jun-18
© 1999, Columbia University