SIP trunking

Session Initiation Protocol (SIP) trunking is the use of voice over IP (VoIP) to facilitate the connection of a private branch exchange (PBX) to the Internet.

In effect, the Internet replaces the conventional telephone trunk, allowing an enterprise to communicate with fixed and mobile telephone subscribers worldwide. (SIP is an IETF standard for initiating interactive multimedia user sessions; a trunk is a line or link that can carry many signals at once, connecting major switching centers or nodes in a communications system.)

In order to take advantage of SIP trunking, an enterprise must have a PBX that connects to all internal end users, an Internet telephony service provider (ITSP) and a gateway that serves as the interface between the PBX and the ITSP. One of the most significant advantages of SIP trunking is its ability to combine data, voice and video in a single line, eliminating the need for separate physical media for each mode. The result is reduced overall cost and enhanced reliability for multimedia services. With SIP trunking, subscribers can:

• Initiate and receive local calls
• Initiate and receive long-distance calls
• Make emergency calls (911)
• Access directory assistance
• Use fixed and mobile telephone sets
• Employ e-mail and texting
• Browse the World Wide Web.

Learn more about VoIP Migration and Implementation

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More resources from around the web: - SIPtrunk.org provides information about all aspects of SIP trunking. - Joel Maloff discusses 'The Many Flavors of SIP Trunking.' - Janne Magnusson of Ingate Systems discusses the benefits of SIP trunking. (PDF)

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