If you’ve spent any amount of time exploring business communications, you’ve probably heard the phrase ‘SIP trunking’ or ‘SIP trunk’ – it’s a pretty common component in the rapidly expanding telecommunications world. In fact, more than 80% of large businesses say that SIP is important to their business. The advantages are irresistable. But what exactly are they? First, a quick overview of the tech at play.

What are SIP trunks? Nothing to do with elephants

First, let’s start with another acronym, VoIP. This stands for Voice over Internet Protocol and is the name for a variety of technologies used to deliver voice calls over data networks, such as the public internet or VPNs, instead of the traditional circuit-switched networks used for telecommunications. As businesses scale up in size, most will use VoIP systems to route calls internally across their data network using a private-branch exchange. This lets them reduce overheads by removing the need to manage separate data and voice networks.

SIP (Session Initiation Protocol) is a signalling protocol used for the real-time delivery of voice and media. With the right infrastructure and interconnections in place, SIP calls can be transmitted between data networks and the public-switched telephone network (PSTN), the global mass of traditional telephone networks operated by national, regional and mobile carriers. So in very simple terms, SIP can be used to enable your on-premise phone systems to make and receive calls via data connections. A virtual phone number, called a DID, can be assigned to your SIP connection so that customers have a phone number to ring when they wish to speak to you.

As for the trunks, they’re nothing to do with swimwear. Think of them as phone lines in old parlance, carrying the voice and media content between two endpoints, which could be VoIP terminals or phones. The beauty of SIP trunks is that you can have as many channels as you want pointing to a single virtual phone number.

This is one of the reasons why they offer significant cost savings compared to traditional telecoms. There’s also no need to invest in expensive onsite infrastructure before using SIP. Integrating your telephony services into your data network and dynamically managing it in the cloud leads to huse ROI savings on existing infrastructure as well, providing variable options to drive cost savings.

What about the other advantages we mentioned earlier?


Unlimited call capacity

SIP trunking allows for unlimited simultaneous call capacity – meaning that you can enjoy as many concurrent calls to and from a single number as you wish! This is especially beneficial for customer contact centers that receive dozens, or even hundreds, of calls a day to a centralised phone number.

Local presence

Because the phone numbers associated with SIP are virtual, they do not need to be tied to your physical location, except in cases where local regulations require this. This means you can use DID numbers and SIP trunks for a two-way voice service that lets you conduct business from your office in Penetanguishene, even though you don’t actually have an office in Penetanguishene and you’re not exactly sure you could pick it out on a map if you had to (hint: it’s in Canada).

If your SIP service provider’s network is fully interconnected with the national telecoms infrastructure in a given country, you will even be able to make domestic calls that are routed in-country, meaning carrier-grade latency, call quality and privacy. You will have access to the entire national dialing plan in that country, including special numbers that can’t be reached by international calling services. They’ll also show up as coming from true local numbers in caller ID, instead of presenting with the international dialing prefix. This is a big deal because local calls are 4x more likely to be answered than international ones.


Centralized comms

If you have multiple business locations, SIP trunking eliminates the need for individual telephone lines at each location, consolidating all branches or offices and creating a single, centralised platform. This results in reduced hardware needs and impressive long-term cost savings. Remember though, that to fully replicate the functionality of the PSTN for business purposes, you’ll need a SIP provider that offers:

  • Inbound voice
  • Outbound voice (domestic and international)
  • Number portability
  • Access to local emergency services numbers

Consolidation of providers

With traditional telephone carriers, you only ever receive coverage in one country, (a handful, if you are lucky) meaning that you need to enter into contracts with dozens of service providers for a global communications footprint.

This can be a migraine-inducing process because of the local regulatory requirements of each country and the lack of consistent processes across borders. A SIP trunk provider will take care of these headache for you, by interconnecting with national networks in each and every country to provide streamlined services around the world. All that’s left for you is to pick a US toll-free number here, a Chinese mobile number there, and whatever else you need.


SIP trunks are extremely flexible, allowing you to scale your communications system on demand as your business grows. You can easily deploy voice services and additional capacity as and when you need it, in offices around the world, without ever having to invest in costly infrastructure.

Learn more about how virtual numbers and SIP trunks can be used to boost your global communications footprint

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