VoIP

VoIP is an acronym for “Voice over Internet Protocol” which is quite simply way of utilizing the Internet (or even in some cases intranets) for telephone conversations. In VoIP, voice is transmitted in digital form in discrete data packets by using Internet Protocol instead of a regular (or analog) phone line which uses circuit-switching technologies. Companies providing VoIP service are commonly referred to as providers, and protocols which are used to carry voice signals over the IP network are commonly referred to as Voice over IP or VoIP protocols. Some protocols used in VoIP are SIP (Session Initiation Protocol), H.323, MGCP (Media Gateway Control Protocol), IAX (Inter-Asterisk eXchange protocol), Skype etc.
Usually the voice data packets are compressed using algorithms to facilitate better transmission of voice over the network.

VoIP is one type of IP Telephony which refers to technology that enables routing of voice conversations over the Internet or any other IP network. Unlike other type of IP Telephony (e.g. Internet Telephony), the transmission of voice signal is done usually done using managed IP-based networks achieving QoS equivalent to PSTN toll quality.

Some VoIP services may only allow us to call other people using the same service, but others may allow us to call anyone who has a telephone number - including local, long distance, mobile, and international numbers. Also, while some VoIP services only work over your computer or a special VoIP phone, other services allow us to use a traditional phone connected to a VoIP adapter. Voice-over-IP is a telephony term describing the facilities for managing the delivery of voice using IP. It involves sending voice information in some digital form in discrete packets rather than in the traditional circuit-oriented format of the PSTN.