Internet Telephony Service Provider

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What Does Internet Telephony Service Provider Mean?

An Internet telephony service provider (ITSP) is an Internet service provider that supplies digital telecommunication service on Voice over Internet Protocol (VoIP). ITSPs provide direct Internet to users or other wholesale suppliers that consequently provide Internet to a home user. The service is based on local telephone and VoIP techniques, and thus it is facilitated by the Internet.


Internet telephony service providers are also known as voice service providers (VSPs).

Techopedia Explains Internet Telephony Service Provider

An Internet telephony service provider uses the oldest method of connecting to the Internet — via local telephone connection attached to an analog adapter that is responsible for connecting to local service providers via a dial-up connection. This establishing of an Internet connection may use an IP phone, or may connect a private branch exchange (PBX) system to the service via media gateways.

An Internet telephony service provider makes use of a number of Internet protocols such as:

  • Session Initiation Protocol (SIP)
  • Media Gateway Control Protocol (MGCP)
  • Megaco
  • H.323 Protocol

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Margaret Rouse
Technology Expert
Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.