2. Basics of protocols David Duffett, Aculab

3. www.voipdeveloper.com August 8-10, 2006 Santa Clara, California Hyatt Regency Santa Clara 3 Our agenda for today Introduction Background A quick game of ‘which protocol am I?’ Strengths and weaknesses Real life examples

4. www.voipdeveloper.com August 8-10, 2006 Santa Clara, California Hyatt Regency Santa Clara 4 Clasp your hands in front of your face Which thumb is closest to your face? Left thumb closest – You are the sexy people Right thumb closest – You think you’re the sexy people But first … a quick test

5. www.voipdeveloper.com August 8-10, 2006 Santa Clara, California Hyatt Regency Santa Clara 5 Introduction What is a protocol? –pro·to·col (prọ tọ -kôl) n. –The forms of ceremony and etiquette observed by diplomats and heads of state –A preliminary draft or record of a transaction –The plan for a course of medical treatment or for a scientific experiment –Computer science – a standard procedure for regulating data transmission between computers

6. www.voipdeveloper.com August 8-10, 2006 Santa Clara, California Hyatt Regency Santa Clara 6 Introduction In the crazy world of VoIP… –We can generally take ‘protocol’ to mean the way in which the calling and called end points must communicate with each other in order to set up, tear down and otherwise manage a session (call) –There are a number of these protocols –Even having two end points claiming to use the same protocol is not a guarantee of a working solution –People interpret the ‘standards’ for their own purposes

7. www.voipdeveloper.com August 8-10, 2006 Santa Clara, California Hyatt Regency Santa Clara 7 Introduction Hello Conversation Goodbye

8. www.voipdeveloper.com August 8-10, 2006 Santa Clara, California Hyatt Regency Santa Clara 8 Background As VoIP has developed, various protocols used for call control have appeared –Telecoms standards bodies –Internet standards bodies –Individual developers trying to solve a problem –Commercial entities

9. www.voipdeveloper.com August 8-10, 2006 Santa Clara, California Hyatt Regency Santa Clara 9 Background For VoIP to work, both (all) the end points involved must use the same protocol for call control – unless a gateway is in use

10. www.voipdeveloper.com August 8-10, 2006 Santa Clara, California Hyatt Regency Santa Clara 10 Which protocol am I? Developed by a telecoms standards body Based on the tried and tested Q.931 Adopted in early VoIP deployments, I am still very much in use today I am very efficient in that I use short codes for messages Some of the really big players developed their systems around me

11. www.voipdeveloper.com August 8-10, 2006 Santa Clara, California Hyatt Regency Santa Clara 11 Yes – I’m H.323 Developed by the ITU Very ‘telecomsy’ way of doing things Good record on compatibility Cisco were heavy H.323 users Early protocol, but still very much in use Used for video sessions, as well as voice

12. www.voipdeveloper.com August 8-10, 2006 Santa Clara, California Hyatt Regency Santa Clara 12 Which protocol am I? Developed by an Internet standards body Arrived at by successful RFCs Most VoIP developers talk about me I use messages that humans can easily understand Some backbone networks are based on me I am very flexible, useable for more than just voice

13. www.voipdeveloper.com August 8-10, 2006 Santa Clara, California Hyatt Regency Santa Clara 13 Yes – I’m SIP (session initiation protocol) Developed by the IETF People contribute RFCs, once agreed they become part of the ‘standard’ Probably more SIP end points than anything else BT’s 21CN is based on SIP Amazing potential with 3PCC (third party call control) The initiated session may be used for voice

14. www.voipdeveloper.com August 8-10, 2006 Santa Clara, California Hyatt Regency Santa Clara 14 Which protocol am I? Originally developed by an individual My name references an Open Source PBX I am bandwidth efficient A lot of end points are capable of supporting me, even though the big players don’t yet use me

15. www.voipdeveloper.com August 8-10, 2006 Santa Clara, California Hyatt Regency Santa Clara 15 Yes – I’m IAX2 (pronounced ‘eeks’) Originally developed by Jared Smith, an Asterisk developer Full name is Inter-Asterisk eXchange version 2 Ongoing development encouraged within the Open Source community Aggregates RTP payloads together in order to make more efficient use of the packet headers, and therefore bandwidth

16. www.voipdeveloper.com August 8-10, 2006 Santa Clara, California Hyatt Regency Santa Clara 16 Which protocol am I? Developed by a commercial organisation I am probably the most widely used protocol today I have been described as a ‘car with hood welded shut’ I enable peer-to-peer voice and video communications I am probably the most widely known VoIP brand

17. www.voipdeveloper.com August 8-10, 2006 Santa Clara, California Hyatt Regency Santa Clara 17 Yes – I’m the Skype protocol Developed around 2003 by the people that brought us the KaZaa file sharing service Uses an overlay peer-to-peer network made of ordinary hosts and supernodes Very little is known of the details of the protocol Great at traversing NATs and firewalls Over 100,000,000 downloads to date

18. www.voipdeveloper.com August 8-10, 2006 Santa Clara, California Hyatt Regency Santa Clara 18 Real life situations Person away on business wants to communicate with their spouse from hotel room –Skype would allow voice and video Same person wants to call normal landlines –Skype Out (costs) –ATA – using IAX2 would remove NAT hassles Telco wants multi-functional network and the ability to separate voice and call control signalling –SIP

19. www.voipdeveloper.com August 8-10, 2006 Santa Clara, California Hyatt Regency Santa Clara 19 In summary VoIP call control protocols are used to set up, tear down and otherwise manage calls H.323 – well deployed, but not seen as the future SIP – all the talk is SIP, has trouble with NATs and firewalls IAX2 – popular with Asterisk installations, on the ascendancy and bandwidth-efficient Skype – the most popular, but bespoke and only for peer-to-peer

20. www.voipdeveloper.com August 8-10, 2006 Santa Clara, California Hyatt Regency Santa Clara 20 In summary Choice of protocol must be a function of requirements, both now and in the future Safe bet is to go with equipment that can support multiple protocols and codecs

21. Thank you david.duffett@aculab.com See us at booth 115