VoIP

Voice over Internet Protocol - VoIP is a general term for a family of transmission technologies for delivery of voice communications over IP networks such as the Internet. Other terms synonymous with VoIP are IP telephony, Internet telephony, voice over broadband (VoBB), broadband telephony, and broadband phone.

VoIP systems employ session control protocols to control the set-up and tear-down of calls as well as audio codecs which encode speech allowing transmission over an IP network as digital audio via an audio stream. Codec use is varied between different implementations (and often a range of codecs are used); some implementations rely on narrow band and compressed speech, while others support high fidelity stereo codecs.

Benefits

• Routing phone calls over existing data networks to avoid the need for separate voice and data networking.
• Conference calling, IVR, call forwarding, automatic redial, and caller ID features that traditional telecommunication companies (telcos) normally charge extra for are available for free from open source VoIP implementations such as Asterisk or FreeSWITCH.
• Costs are cheaper, mainly because of the way Internet access is billed compared to regular telephone calls. While regular telephone calls are billed by the minute or second, calls are billed per megabyte (MB). In other words, calls are billed per amount of information (data) sent over the Internet and not according to the time connected to the telephone network. This makes it cheaper, because the amount charged for the data transferred in a given period is far less than that charged for the amount of time connected on a regular telephone line.

Voice over Internet Protocol can facilitate tasks and provide services that may be more difficult to implement using the PSTN. Examples include:

• The ability to transmit more than one telephone call over the same broadband connection. This can make it simple to add an extra telephone line to a home or office.
• Secure calls using standardized protocols (such as Secure Real-time Transport Protocol.) Most of the difficulties of creating a secure phone connection over traditional phone lines, like digitizing and digital transmission, are already in place. It is only necessary to encrypt and authenticate the existing data stream.
• Location independence. Only an Internet connection is needed to get a connection to a VoIP provider. For instance, call center agents using VoIP phones can work from anywhere with a sufficiently fast and stable Internet connection.
• Integration with other services available over the Internet, including video conversation, message or data file exchange in parallel with the conversation, audio conferencing, managing address books, and passing information about whether others, e.g., friends or colleagues, are available to interested parties.