IP phone system (also called voice over Internet protocol) is a process and a set of technologies that permit multimedia and voice communications to be transmitted via the internet protocol (IP network). The terms IP telephony, broadband telephone, and broadband telephony service refer to the delivery of communications services (voice messaging text, fax, SMS and audio messaging) via the public Internet or through private internet connections instead of via the PSTN, the public switched telephone network (PSTN).
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