Wednesday, February 9, 2011

Getting Down to Business with VoIP (Chapter 1)

Technological innovation is hurling itself upon us once again.  This time, it’s coming in the  form of improving the  way we communicate, bringingtelephone  call. with it new capabilities that change the  meaning of the  phrase VoIP (often pronounced “voyp”)  is the  name of this  new communications technology.

VoIP, which stands for voice  over Internet protocol, basically means voice transmitted over  a digital  network. Well, that isn’t technically accurate because the  Internet isn’t strictly necessary for VoIP, although it was at first. What is necessary for VoIP technology is the  use of the  same protocols that the  Internet uses. (A protocol is a set  of rules used to allow orderly communi- cation.) Thus,  voice  over Internet protocol means voice that travels by way of the  same protocols used on the  Internet.

VoIP is often referred to as IP telephony (IPT) because it uses Internet protocols to make enhanced voice  communications possible. The Internet protocols are the  basis of IP networking, which supports corporate, private, public, cable, and  even  wireless networks. VoIP unites an organization’s many locations — including mobile workers — into a single  converged communica- tions network and  provides a range of support services and features unequalled in the  world of telephony.



Technically, IPT refers to telephone calls carried over  the  organization’s local area  network (LAN) such as a single  building location, a campus-like network, or even  a LAN within your  home. When IPT crosses from the LAN to the  WAN or any other external network, including other LANs operated by the  same company at distant locations or the  Internet, it becomes VoIP.


In the Beginning, There Was POTS

Before digital  networking took  off, everyone had  to use the  one and  only POTS, which stands for plain old telephone service  (honestly, it does). POTS runs over  a network called the  PSTN, or public switched telephone network. These POTS telephone systems use the  tried-and-true method of telephone service known  as circuit-switched.  (See Chapter 2 for more about the  history of POTS, the  PSTN, and  the  operation of circuit-switched telephony.)

For customers, the  costs related to the  regulated circuit-switched PSTN remain much higher than they  need to be. Consumers as well as companies that must rely on POTS on a daily basis know what  the  POTS way of tele- phony means to their bottom line. The good  news  is that VoIP is an alterna- tive that can greatly reduce or eliminate POTS-related costs. (Chapter 3 fully details the  recurring charges of the  POTS way of doing  telephony.) VoIP also enhances productivity, leaving  more  money in the  budget to do other things besides pay telephone bills.


From POTS to Packets

VoIP technology enables traditional telephony services to operate over com- puter networks using  packet-switched protocols. Packet-switched VoIP puts voice  signals into packets, similar to an electronic envelope. Along with the  voice  signals, the  VoIP packet includes both the  caller’s  and the  receiver’s net- work addresses. VoIP packets can traverse any VoIP-compatible network. Because VoIP uses packets, much more information can be carried over  the  network to support and  enhance your communication needs when  compared to traditional telephony methods.

In a circuit-switched network such as POTS, routing is less  dynamic than with a packet-switched network. In the  POTS world, if a line is down,  the call can’t go through. In a packet-switched network, multiple routes can be established, and packets can travel any of the  available routes. If one of the lines  support- ing the  network is down,  the  packet can switch to another working  route to keep  the  call up.

With VoIP, voice  signals can travel the  same packet-switched network infra- structure  that companies already use for their computer data. Chapter 7 goes  into more  detail  about dedicated packet-switched networks that  support VoIP.

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