Voice over Internet Protocol (VoIP) is a form of communication that allows you to make phone calls over a broadband internet connection instead of typical analog telephone lines. Some VoIP services require a computer or a dedicated VoIP phone, while others allow you to use your landline phone to place VoIP calls through a special adapter.
VoIP can be configured using dedicated routers, USB adapters, software-controlled VoIP applications, or dedicated VoIP phones. When considering VoIP service, do not assume that its features, functionality, and options will equal those of traditional landlines; you should be familiar with the requirements, availability, and possible service limitations of VoIP service before switching to VoIP.
This paper describes the requirements, availability, and possible service limitations of VoIP services as well as the threats and risks associated with their use. Also described are strategies for protecting yourself against VoIP risks.