VoIP

Voice over Internet Protocol (VoIP) is the transmission of voice using the Internet Protocol (IP).

Traditionally, voice services make use of circuit switching to transmit voice signals. This means that a channel is set up and maintained between the calling party and the called party for the duration of the call. In VoIP, the voice signal is encoded and divided into packets of data. Each packet is sent separately through the network.

Packetizing of the voice signal means that nothing will be sent when the caller is not speaking. This allows for a reduction of the total bandwidth required. Another benefit of VoIP is the ability to route voice traffic over the internet. This gives the ability to get international calls at very low rates.

There are different VoIP services. They can be divided in the following types:

• Internet telephony
  In this case, both parties install software on their computer to telephone each other. Examples of software are Skype and MSN.
• IP telephony
  In IP telephony a telephone is connected to an IP network. Access can be provided by the Internet Service Provider or an independent third party.
• Corporate internal use
  In this case IP is used to route voice over the internal data network of a company.
• Carrier internal use
  Carriers also make use of IP to route voice over their network.