A Quick Introduction to Voice over Internet Protocol

A Quick Introduction to Voice over Internet Protocol (Vo. IP) PURC Annual Conference 2004 Chuck Jackson PURC 2004

Roadmap • Basics of packet communications as used in the Internet • How voice is transmitted over packet networks such as the Internet. • Examples of Vo. IP uses and systems • Concluding thoughts PURC 2004

Internet Basics • The basic building block of networks is the IP datagram. • Analogy to datagrams—a postcard with – Destination address – Return address – A small amount of text • A postcard might inform you of a friend’s holiday travels or remind you of a dentist’s appointment. • The postal service doesn’t care which application (friend or dentist) sent the postcard—it just carries processed wood pulp with black marks. PURC 2004

Protocol Layering Applications (e. g. , email, web pages) TCP UDP IP (Internet Protocol) Physical Transport (e. g, Cable Modem) A Typical IP Datagram IP Header (20 bytes) PURC 2004 TCP Header (20 bytes) Email Data (1000 bytes)

The Hourglass Figure PURC 2004 Source: Steve Deering, IETF 51

Voice—Another Application over IP • Voice requires about 10, 000 to 100, 000 bits per second. • Can send those bits over IP—just as we send web pages or email. PURC 2004

Alternative Vo. IP Architectures • PC to PC Internet PURC 2004

Alternative Vo. IP Architectures • Phone to Phone via the Internet PURC 2004

Alternative Vo. IP Architectures • Phone to Internet to Gateway to PSTN Internet GATEWAY PSTN PURC 2004

Alternative Vo. IP Architectures • PSTN to Gateway to Internet to Gateway to PSTN Internet GATEWAY PSTN PURC 2004 GATEWAY PSTN

Vo. IP Examples • • • Xbox Voice Windows messenger AOL Instant Messenger Motorola Phone Adapter (Vonage) Cisco Phone Cox Cable in Hampton Roads, Virginia PURC 2004

Xbox Live PURC 2004 http: //www. xbox. com/en-US/live/about/Starter. Kit-Retailers. htm

Microsoft’s Explanation of the Benefits of Voice with Xbox PURC 2004 http: //www. xbox. com/en-US/live/about/Article-Top 10 Get. Live. ht

Microsoft Windows Messenger PURC 2004

AOL Instant Messenger PURC 2004

The Motorola Box Used by Vonage PURC 2004

Vonage Uses this Archtecture • Phone to Internet to Gateway to PSTN Internet GATEWAY PSTN PURC 2004

Motorola Box in Vonage Architecture Internet GATEWAY PSTN PURC 2004

Cisco 7970 IP Phone PURC 2004

Cox Cable in Hampton Roads, Virginia PURC 2004

Concluding Thoughts • Vo. IP is one of many higher-level communications capabilites among devices connected to the Internet. • Vo. IP is not an application. • Vo. IP is a capability that is part of many applications. • Vo. IP capabilities are already pervasive. – Microsoft Windows Messenger (part of XP) – AOL Instant Messenger – Xbox and Sony Playstation PURC 2004