Voice over Internet Protocol (VOIP) is the mechanism of placing voice calls over the Internet rather than over analog telephone lines. In the beginning, VOIP Calls were restricted from computer-to-computer. However, it is now possible to place calls to landlines and mobile phones using VOIP capabilities. This feature has been largely possible due to the emergence of Internet Protocol (IP)-based Next Generation Networks (NGNs). They continue to replace the traditional circuit switch networks commonly referred to as Public Switch Telephone Networks (PSTNs). VOIP is sometimes referred to as Internet telephony, IP telephone or Digital telephone.
Over the years, there has been a rapid increase in the use of VOIP by consumers largely due to the low rates on offer. In some cases like Skype, calls could be placed free of charge, of course with an internet connection. On the part of telecom providers, it is an opportunity to slash the cost of placing calls as it is cheaper to place calls over the IP based networks than the PSTNs. For example, incumbents in Bangladesh, Fiji, Ghana, Tunisia, and Sudan all use VOIP for the transmission of their International calls (ITU News, Sept 2009)
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