Voice over Internet Protocol (VoIP) adalah teknologi yang dapat mentransfer voice (suara) dengan menggunakan circuit-switched networks atau over IP networks. Komunikasi menggunakan Voice over Internet Protocol (VoIP) untuk perusahaan mempunyai banyak keunggulan dibandingkan dengan telepon tradisional (traditional phone) dengan PBXs based : dari segi biaya jelas relatif murah, walaupun internasional call tetap dengan biaya pulsa lokal (saving cost), juga semakin beragam aplikasinya (application benefit). Adapun tujuan dari skripsi adalah membandingkan Internet Protocol Telephony pada Voice over Internet Protocol yang ada di Indonesia dengan cara membandingkan aplikasi IP Telephony melalui PSTN (Public Switched Telephone Network) dan VoIP (Voice over Internet Protocol).

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Voice over the Internet Protocol (VoIP) is technology that could transfer voice with us circuit-switch networks or over IP networks. Communication us Voice over the Internet Protocol (VoIP) for the company had many superiority compar with the traditional telephone (traditional phone) with pbxs based: from the aspect of the clear cost relatively cheap, although international call continue to at a cost of the local pulse (saving cost), also increasingly heterogenous his application. As for the aim of the final project of being to compare the implementation the IP Telephony by means of comparing the application IP Telephony through PSTN and VoIP.