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 or other packet-switched networks. Other terms frequently encountered and synonymous with VoIP are IP telephony, Internet telephony, voice over broadband (VoBB), broadband telephony, and broadband phone.
VoIP systems usually interface with the traditional public switched telephone network (PSTN) to allow for transparent phone communications worldwide.
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 of VoIP (and often a range of codecs are used); some implementations rely on narrowband and compressed speech, while others support high fidelity stereo codecs.
Benefits
Operational cost
VoIP can be a benefit for reducing communication and infrastructure costs. Examples include:
* Routing phone calls over existing data networks to avoid the need for separate voice and data networks.
* 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.
Flexibility
VoIP 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 VoIP a simple way 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 with VoIP. 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.
Rabu, 18 November 2009
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