SIP Trunking is a signaling protocol used to create, manage, and terminate sessions in an Internet Protocol (IP) based network.

Session Initiation Protocol (SIP)


SIP Trunking is a signaling protocol used to create, manage, and terminate sessions in an Internet Protocol (IP) based network.

A session could be a simple two-way telephone call or it could be a collaborative multi-media conference session. This makes possible services like voice-enhanced e-commerce, web page click-to-dial or Instant Messaging with buddy lists in an IP based environment. It should be noted that the job of SIP is limited to only the setup and control of sessions. The details of the data exchange within a session e.g. the encoding or codec related to an audio/video media is not controlled by SIP and is taken care of by other protocols.


Benefits include:

  • Eliminates the need to invest in costly (and less capable) TDM1-gateway equipment infrastructure or desktop equipment
  • Nullifies the need to purchase equipment, such as managed-media gateway devices, to interface between IP voice and the PSTN2
  • Provides point of presence 3 in multiple U.S. cities so that companies can establish local numbers rather than rely on an 800 number
  • Accesses the benefits of a hosted VoIP service, without discarding
  • IP trunks can offer significant cost-savings for enterprises, eliminating the need for local PSTN gateways, costly ISDN4 (Integrated Services for Digital Network), BRIs5 (Basic Rate Interfaces) or PRIs6 ( Primary Rate Interfaces)


Let us help you decide. We will meet with you and discuss your business needs, explain the pros and cons of different SIP Trunking carriers, and walk you through the selection process. Once you’ve decided on a carrier, we’ll work with you to design your network, identify cost-savings, place your order, manage your project and work directly with the carrier throughout the implementation. All the while, you can continue to do what you do best - run your business.

Common Acronyms

  • TDM - Time Division Multiplexing transmits data by breaking the signal down into multiple segments, which are transmitted separately over a single signal. Data then is reconstructed at the receiving end using a method based on the timing of the transmission.
  • PSTN – Public Switched Telephone Network is the aggregate of the world’s circuit-switched telephone networks that are operated by national, regional, or local telephony operators, providing infrastructure and services for public telecommunication.
  • POP – Point of Presence is an artificial demarcation point or interface point between communicating entities.
  • ISDN – Integrated Services for Digital Network is a set of communications standards for simultaneous digital transmission of voice, video, data, and other network services over traditional circuits of the public switched telephone network.
  • BRI – Basic Rate Interfaces is an Integrated Services Digital Network (ISDN) configuration intended primarily for use in subscriber lines similar to those that have long been used for voice-grade telephone service.
  • PRI– Primary Rate Interfaces is a standard telecommunications service level within the Integrated Services Digital Network (ISDN) specification for carrying multiple DS0 voice and data transmissions between a network and a user. DS0 is a basic digital rate of 64 kbit/s corresponding to the capacity of one voice-frequency-equivalent channel.