Chapter 17
Saving Money with VoIP (Voice Over Internet Protocol)
In This Chapter
Protocols in this chapter: IP, UDP, RTP, RTCP, SIP, SRTP, SRTCP, MGCP, H.323
Understanding what VoIP is
Getting the VoIP hardware and software
Examining the five steps to making or receiving VoIP calls
Looking at how VoIP packets move through the layers
Preventing security attacks on VoIP calls
As far as TCP/IP is concerned, there’s no difference between types of data; that is, text, binary, video, and voice are just plain data. Because TCP/IP sees voice and video as just data, you can transmit more than e-mail and files over the Internet. You can make and receive phone calls and videoconferences across the Internet, with no telephone company involved. VoIP, pronounced “voyp,” stands for Voice over Internet Protocol, or Voice over IP.
Some other names for VoIP include broadband phone, broadband telephony, Internet telephony, IP telephony, and VOBB (voice over broadband). We call it VoIP in this book.
Getting the Scoop on VoIP
People usually think of VoIP as Internet voice conversations. That’s true, but VoIP can use any TCP/IP network for voice conversations. Employees can call each other over the corporate network even if the network doesn’t connect to the Internet.
In a traditional telephone call, your voice travels over your phone company’s land lines and undersea cables. Your phone company’s land lines inter-operate with other phone companies’ lines all over the world to make global calling possible. ...
