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VoIP Brief overview

VoIP Brief overview

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VoIP Brief overview

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  1. VoIPBrief overview Miloš Stojanović

  2. What is VoIP ? • Voice over IP • Internet Telephony, IP Telephony, Digital Phone • Real-time voice communication Miloš Stojanović

  3. Basic concept Telephone Adapter Modem / Router Internet PC with software phone Modem / Router Miloš Stojanović

  4. Requirements • IP-based network infrastructure • QoS capabilities • Packet loss, jitter, delay • Software / Hardware • VoIP carrier (DID) services • Direct Inward Dialing, assigning numbers • PSTN <-> VoIP Miloš Stojanović

  5. Technologies & Protocols • Audio codecs (Speex, G.729, etc) • Communication protocols • Based on (S)RTP • H.323 • SIP Miloš Stojanović

  6. H.323 • Early availability of standards • Originally created for multimedia applications distribution over LAN • Flexible addressing mechanisms • URI, email addresses, E.164 (PSTN), … • Voice, video and data conferencing • Used by largest carriers in core backbones Miloš Stojanović

  7. SIP • Session Initiation Protocol • Lightweight • Text based – human readable control messages • Transport-independent • TCP, UDP, ATM, … • Limited addressing (SIP-URIs only) • Some video and no data conferencing support. No video packet loss recovery Miloš Stojanović

  8. VoIP Pros • Cost • PSTN - 37 din/min (Serbia to US) • VoIP – 10 din/min (Serbia to US) • PC-to-PC – no expenses ! • Functionality • Easy management and administration via PC • Re-Routing calls • No need for dual-network infrastructure Miloš Stojanović

  9. VoIP Cons • Reliability • Power outage, IP connectivity, emergencies • Vulnerability • Malware, man in the middle, spam, etc • Quality • QoS, multipath routing, redundant packets • Wasted bandwidth • Packet headers wrapping, silence suppression Miloš Stojanović

  10. Popular software solutions (1) • Skype • Freeware (closed source) • Proprietary protocol • Peer to peer (decentralized) model • Supernodes • Windows Live Messenger (MSN) • SIP compatibility Miloš Stojanović

  11. Popular software solutions (2) • Ekiga • Under GPL • SIP • Linux only • Google Talk • Freeware • Based upon XMPP Miloš Stojanović

  12. Evolution tendencies? • VoIP as mainstream • Make PSTN obsolete • Mobile VoIP • Voice over WiFi, over WiMax • Future of cell phones? Miloš Stojanović