VoIP Basics

VoIP is a set of technologies that transport voice (audio) signals as data through the Internet. Unlike audio streaming which is a one way transmission, VoIP uses bi-directional protocols as all ends should be able to transmit and receive.

VoIP has been around for while, however, it wasn’t feasible for use for most users due to transfer speed limits (narrowband connections). In order to convert your voice into data, a codec (Coder-Decoder) is used. The more compressed the voice, the smaller the packet, but also the more processor power required to compress and de-compress the received packets.

Therefore, when speed wasn’t an issue, processing power was, and when a low compression codec was used to avoid using too much processor power, the data packets were too big and speed became an issue. When  broadband connections became a standard in most countries and processing power became cheaper, VoIP emerged as a ground shattering technology and currently it isused by most telecommunication companies worldwide.

VoIP is used to cut down costs because instead of having a call going through several providers, switches and trunks (each one from a different company and each compay having a small cut), it takes your call and uses the Internet to send it to it’s destination city, hitting the PSTN (public switched telephone network – the regular phone network) only as it’s “taken out” of the Internet and sent through a local phone call to the called party.

Even though some people hasn’t heard about VoIP or thinks they haven’t used it, most big telecommunication companies, mobile operators and calling card operators use VoIP to cut down their costs so it’s pretty safe to say that most people have “used” VoIP unknowingly. To help you fully understand this VoIP world, here are some terms and acronyms that you probably want to know:

SIP : Session Initiation Protocol. One of the most widely used VoIP protocols.
H.323 : an ITU standard protocol.
IAX : A new VoIP protocol introduced by Asterisk (Digium).
Codec : Short for Coder-Decoder, algorithms used to convert audio into data.
DID : Direct Inward Dial. A phone number mapped to VoIP.
CDR : Call Detail Records.
PDD : Post dial delay, delay after a number is dialed until the call is connected.
ASR : Answer seizure ratio. Ratio of correctly connected/answered calls.
IP phone : Phone that connects to a network instead of a regular phone line.
ATA : Analog Telephone Adapter. Briges regular phones and IP networks.
 Rate center : Numbers within the same area code.
 IVR : Interactive voice recording. Recordings that interact with the caller via menus.
 PBX : Public branch exchange. Systems that interconnect extensions and phone lines.
 Asterisk : The most widely used open source PBX.
 A 2 Z : The entire world.
 Direct route : Channels to route calls to a specific destination.
 Softphone : Software based phone.