Voice over Internet Protocol
Also known as VoIP, IP Telephony, Internet telephony, and Broadband Phone. It is usually assumed that the "voice" in VoIP refers to the complete set of telephony functions: voice, fax, DTMF, data, etc. This makes purists cringe, but "telephony" just has too many syllables.
Basically, VoIP is the routing of voice (and telephony) conversations over an IP-based network, especially the internet. This means that the voice data must be packetized so that it can flow through a general-purpose, packet-switched network instead of traditional dedicated, circuit-switched telephone transmission lines.
VoIP may be implemented using proprietary protocols (e.g. Skype), but most commercial implementations more or less adhere to standard protocols.
"Push to Talk over Cellular" (PoC) or simply "Push-to-Talk" (PTT) are common names for mobile VoIP solutions.
Key sources of VoIP knowledge:
- Henning Schulzrinne, Columbia University
- Packetizer > VoIP
- OMA Push to talk Over Cellular V1.0
Some online VoIP Magazines, Information Guides, and Tutorials:
- VOIP Wiki - a reference guide to all things VOIP
- VoIP User
- VoIP News: VoIP Books Voice over IP
- Compare Consumer VoIP Providers
- VoIP Lowdown
- International Engineering Consortium (IEC) VoIP Tutorial
- Daily Payload
Some Open Source VoIP Projects:
- Open Source Erlang - Megaco/H.248 corner
- VOIP Wiki - Open Source VOIP Software
- Asterisk, The Open Source PBX
- Vovida: Creators of VOCAL
Some Vendor Sites:
- Cisco IP Communications and Voice Products
- Skype Journal (not affiliated with Skype)
- Protocols.com (RADCOM)
- SJ Labs