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SIP Trunking - What You Need to Know

Sep 4, 2017

What is SIP Trunking?

Session Initiation Protocol (SIP) trunking is a process by which business phone systems can be used through an internet connection, rather than through a phone-based land line. This functionality is sourced through a private branch exchange (PBX), which assists in establishing internal telephone communication within a company.

There are two forms of PBX, on-premise and hosted. On-premise PBX uses analog hardware to facilitate its processes, while hosted PBX is facilitated through the cloud. For the sake of SIP trunking, which operates digitally, hosted PBX is the only true option.

How Does SIP Trunking Differ From Hosted VoIP?

Voice over Internet Protocol (VoIP) is a digital service which allows a user to make calls through an internet connection rather than through a local phone service provider. To that end, while VoIP focuses solely on voice-based services, SIP trunking can transmit all kinds of media, including video and raw data.

Benefits to SIP Trunking

  • Cheaper than systems reliant on traditional phone lines. Costs associated with hardware, installation, and maintenance are not necessary.
  • It is much easier to scale systemic needs with business increases. This is achieved through an increase in bandwidth, rather than the addition of physical infrastructure.
  • All calls are treated as local, thus saving costs associated with long distance communication and 1-800 numbers.
  • Can be purchased in smaller amounts, at lower rates, which eliminates large-scale subscriptions.
  • Increased reliability as compared to classic phone networks.

Cons of SIP Trunking

  • Older devices, such as fax machines and wired alarms, may encounter compatibility issues.
  • If only one connection is used for all locations and inputs, it can result in a lack of redundancy. In the event of a crash, all data could be lost.
  • Blocks geolocation services, such as those used by enhanced 9-1-1 call centers.
  • Fewer security barriers. Since SIP trunking streamlines voice and data, hackers will only need to penetrate one system.

Companies That Offer SIP Trunking


Nextiva offers unlimited calling and a contract-free agreement. The setup process is free, and a 30 day money back guarantee is offered.


Intermedia boasts a scalable cloud-hosted PBX phone system. With free installation and a financially-backed service guarantee, the company offers a comparable service to similar providers.


Aiming for a streamlined service model, ClarityTel offers flat-rate pricing and no primary rate interface. At As with Nextiva, a money back guarantee is offered for the first 30 days, as is the prospect of free installation.


ShoreTel offers large-scale phone conferencing, as well as CRM integration. ShoreTel’s SIP trunking can be cancelled at anytime, though usage fees may apply.

Vonage Business

Vonage Business offers over 40 premium features without any installation fees. While contract-free, the first 30 days are treated as a free trial. Subsequent months are priced based off either unlimited use or metered service. Vonage allows for cancellation anytime, with no associated fees.

SIP trunking is a great way to bring corporate communication into the 21st century. It cuts corporate reliance on phone companies, as well as provides protection from systemic outages. If SIP trunking is of interest as it relates to the purchase of a business phone system, then a perusal of our top 10 providers is recommended.