1. Tom Behrens Adam Muniz

2. Overview What is VoIP SIP Sessions H.323 Examples Problems

3. What is VoIP Voice Over IP Internet as Telephone Network Converts Analog Audio to Digital Audio Eliminates Circuit Switched Network Communicates over Packet-Switched Internet SIP & H.323 Protocols

4. SIP – Session Initiation Protocol Designed by IETF Application Layer Established, Manages, and Terminates a Multimedia Session Two-Party, Multiparty, Multicast Sessions Independent of the Transport Layer Runs on UDP, TCP, or SCTP SIP Messages INVITE, ACK, BYE, OPTIONS, CANCEL, & REGISTER

5. SIP Addresses sip:address Telephone Email IP

6. Simple Session using SIP Establishing a Connection Three-Way Handshake INVITE, Reply Message, ACK Communicating Use Two Temporary Ports Terminating a Connection BYE

7. Simple Session using SIP

8. Tracking the Callee Callee is at a Different Location Registrar Server knows Callee Location Email Address INVITE -> Proxy Server Proxy Server Sends INVITE to Callee

9. Tracking the Callee

10. H.323 Allows Telephones on the Public Telephone Network to talk to Computers Gateway Connects the Internet to the Telephone Network Translates Messages Gatekeeper Registrar Server on a LAN

11. H.323

12. H.323 Operation Terminal sends a broadcast message to the Gatekeeper Gatekeeper responds with its IP address Terminal and Gatekeeper negotiate bandwidth Terminal, Gatekeeper, Gateway, and Telephone negotiate compression method Terminal, Gatekeeper, Gateway, and Telephone exchange audio Terminal, Gatekeeper, Gateway, and Telephone terminate communication

13. H.323 Operation

14. Examples Skype Vonage Cisco Systems Telephones

15. Problems No Power or No Internet, No Phone Poor Internet connection leads to a poor phone connection Security Threats Identity/Service Theft Viruses, malware, spamming, and phishing attacks