improving your SIP trunking

SIP Trunking 101: The Fundamentals

SIP trunking is taking the business world by storm. According to Transparency Market Research, the global SIP trunking services market could grow at a 13% annual rate until 2030, meaning SIP trunking could reach a US$ 35.5 billion market value by the same year. How is this technology changing the way companies communicate?

People daily communicate via chat, voice or video call, often not knowing they do so with SIP trunking technology’s support. Businesses are also generally unfamiliar with how exactly SIP services work or what to expect from them. Let’s clarify some of the fundamentals of SIP trunking, including its meaning and how it works, without confusing industry jargon or unexplained acronyms.

What is SIP Trunking?

SIP stands for Session Initiation Protocol and entails sending unified communications services across the internet, meaning SIP trunking is the consolidation of multiple branches, or channels, of individual SIP sessions.

Trunking multiple SIP sessions is accomplished through another technology called IP-enabled PBX (Private Branch eXchange), which is essentially a private phone network that expands on the phone-system features that matter to businesses most.

SIP trunks running on PBX networks are basically virtual phone lines that enable users to make and receive phone calls over the internet to anyone in the world with a phone number. SIP trunks utilize a packet switch network, in which voice calls are broken down into digital packets and sent across a network to the final destination.

Before SIP became a popular and reliable method of transmitting voice signals, the Public Switched Telephone Network (PSTN) carried all telephone calls. The PSTN is the network that has those copper phone lines we traditionally associate with the “telephone.” The PSTN is a circuit-switched network, which requires a physical connection between two points to complete a call.

In contrast, each SIP trunk supports multiple SIP channels (a SIP channel being equivalent to one incoming or outgoing call). The number of different channels that a SIP trunk can contain is unlimited, so your business only needs one SIP trunk no matter how many concurrent calls you expect. The number of channels required depends on how many calls your business will make at any one time.

Related: How To Explain to Your Customers How SIP Works in VoIP

SIP, VoIP, and Other Related Terms

There are a few important terms to define in order to understand the basics of SIP trunking. Top SIP providers will provide solutions that do not require an IT or telecom background for you to enjoy the benefits. However, it is still extremely helpful to understand the fundamentals of SIP technology in order to get the most out of it.

SIP vs. VoIP

Although people often use SIP and VoIP interchangeably, they are not the same thing. VoIP stands for Voice over Internet Protocol. This broad term covers any phone calls made over the internet, and it includes a group of protocol technologies, of which SIP is just one example. It could therefore be said that SIP enables VoIP as one of its specific protocols – but not all VoIP is SIP.

Voice Codecs

VoIP technologies, including SIP, require codecs to translate analog frequencies into digital data or one digital format into another. Codecs convert audio voice signals into compressed digital formats for transmission over the internet. When the signal reaches its destination on the network, the codec converts it to an uncompressed audio signal for replay. It’s what makes VoIP possible.

Different codecs have different levels of compression. The two most popular codecs for SIP trunking are G.711 and G.729. G.711 provides an uncompressed high-quality voice, while G.729 is compressed to use less bandwidth at the cost of sound quality.

Carrier Tiers and Call Quality

Excellent audio quality is essential for any business communication system, especially those that are customer-facing. The best carrier solutions offer voice quality virtually indistinguishable from traditional landlines – but it is critical to be diligent about the grade of the carrier network used by your SIP provider. Only Tier-1 carriers connect directly to the backbone of the internet for the highest possible call quality and reliability.

Tier-1 Carriers

Tier-1 carriers are large enough to be independent of other network providers and do not require paying other network providers for use of the network (in technical terms, they operate on “settlement-free peering”). As such, Tier-1 infrastructure is to the internet as copper wires are to traditional PSTN landlines. Similarly, Tier-1 networks match the ability of PSTNs to provide nationwide telephone coverage – and even further, an unimpeded global network.

Tier-2 and Below

Tier-2 carriers are instead reliant on the permission of Tier-1 carriers, purchasing IP transit from them in order to obtain full access to the internet. They must contend with many other similarly sized peers vying for network access, creating competition that doesn’t always benefit the end-users as much as the Tier-1 carriers themselves. As such, companies reliant on Tier-2 carriers are more likely to be subject to service changes and experience less reliability than those working directly with Tier-1 carriers.

When it comes to call quality and long-term reliability, businesses that can obtain access to Tier-1 carriers should do so. Since the speed of business depends on the speed and reliability of their communications, there is little reason to chance it with Tier-2 providers who only indirectly connect their customers to the infrastructure that Tier-1 providers themselves control.

Router Setting: Quality of Service (QoS)

Quality of Service (QoS) is a router setting used to tell the network to prioritize voice calls over other data traffic. Minor delays in the signal reaching the network or a bit of data loss aren’t things users consuming data will notice – but they can wreak havoc with voice calls, where even minor latency delays can result in significant communication errors. Enabling QoS ensures audio quality remains high, even while other data-intensive activities are taking place.

For instance, if your business is downloading large files or streaming video content, any voice or video call that takes place can be given priority access to bandwidth for as long as the call is taking place. After the call, that priority bandwidth is freed up, and the downloads can speed up again. Efficient application of Quality of Service settings ensures that the networking services that matter most to your business have constant access to the digital express lane when they need it.

Related: What to Look For in a SIP Provider?

Why Choose SIP?

There are many far-reaching benefits to transitioning to SIP for your business. One of the most important is a major reduction in communications costs.

In many cases, unlimited local and long-distance calls to most of North America are bundled in with the monthly fee for each SIP channel. What’s more, top SIP providers allow you to provision channels on-demand, meaning you get and pay for only the number of channels you need now and can quickly scale at any time to suit your business needs.

Additional benefits include built-in business continuity features, network consolidation, and unified communication features like video, presence, application integration, and instant messaging.

How to Choose the Best SIP Trunking Provider?

The market for SIP services is highly active, and you may find a broad range of options in the industry – meaning SIP trunking services suited to the needs of businesses are not all created equal.

How, then, do you choose the best SIP trunking provider for your company? There are several essential criteria:


A reputable partner will offer platform interoperability, meaning they can customize their services to your unique business communication needs instead of offering a cookie-cutter approach. Just as the most robust apps and other software are capable of being run on any operating system, a reliable SIP trunking system should be capable of operating in a wide variety of digital environments.

To save yourself time, ask your Head of IT which network systems your company relies on, and ask prospective SIP providers if their services work reliably with them. Ask the same of any system you may have plans to upgrade in the future.

Real-time data

Your chosen SIP provider should make as much real-time data available to you as possible. This data (for instance, call records) will help you drive your sales, marketing, and customer service strategies by providing invaluable metrics of performance.

Data protection

A reputable SIP trunking provider will focus on protecting your customer’s data. Find out what security measures they have to protect against security issues such as toll fraud, malware, and various hacking methods in general. Be sure to inquire about their security protocols for not only your company, but their own as well.

Ask them to show you where you can find their written, legally binding policies related to privacy and data sharing. Your trade secrets are valuable, and competitors or digital thieves may take an interest in anything you place online, meaning SIP trunking providers must provide leading-edge security protocols just as you’d expect with any other digital asset protection.

Internet provider choice

Top suppliers will allow you to choose your own internet provider, which will make the SIP trunking services available in as many locations as possible. The major benefits of versatility and network cohesion are made possible through choice, and being able to use the internet service provider you already have a good relationship with is essential to ensuring your new SIP service conforms to your needs.


True SIP industry leaders should provide not only a low-cost option for migrating to new SIP trunking services, but also the ability to directly configure their service for operation with almost any brand of IP-PBX or softphone. If you’ve already set up a SIP trunking system in the past and found it functional but want to upgrade it, inquire about your new prospective SIP provider’s ability to use what is already there.

Also keep an ear out for the opportunity to upgrade services, even if you are happy with them – and be wary of any pressure to instead downgrade your current system. The best SIP provider should not ask you to compromise on versatility.


To ensure business continuity, ask about redundancy capabilities to seamlessly route calls in case of network failure. This is a key benefit of SIP trunking, with meaning that is sometimes lost on many SIP providers. SIP telephone networks can easily provide redundancy services that would be equivalent to having multiple hard-wired lines for a PSTN – and you’re missing out if you don’t ensure your SIP provider takes full advantage of this capability.


Verify if the provider you’re considering offers comprehensive training for SIP trunking and related technology. You and your stakeholders should expect no less, and expert training will go a long way to ensure that your new investment functions at the highest level right out of the gate.

Customer service

Your SIP trunking platform should offer expert tech support for any and all technical needs, and it’s important that your SIP provider is as readily available as (or even more than) you’d expect from a landline provider. If your communications system goes down, so too do does your profitability until it is up again. Superior customer support will also give you insight into the general level of professionality and expertise of your SIP Trunking provider.

Carrier troubleshooting

The best SIP trunking providers will help you solve any carrier-related issues that may pop up. This is one of the major benefits of selecting a Tier-1 SIP trunking service because they will work directly with the entities controlling the network itself. The alternatives will have you depending on the strength of their relationships with other companies, which even if good requires contending with more moving parts and needlessly introducing system complexity.


Check on the level of automation your potential provider offers. Are their implementation, monitoring, and maintenance procedures remote and easy to manage? You’ll want to reduce the need for human intervention as much as possible while at the same time being confident that you or they can easily detect early signs that the system could be simplified.


Evaluate the SIP provider’s pricing model; is it straightforward and transparent? Do they require a lengthy contract and other restrictive terms? Are there monthly fees or upfront investment requirements? Top partners will offer prepaid and no-contract services with affordable monthly payments per unlimited SIP trunk channel. You should then be allowed to add, cancel, or upgrade channels at any time with a simple online control panel.

Free trial

Ask if your provider offers a free trial, so you can test the service and experience the benefits of SIP trunking first-hand before investing. Getting started on the best new footing requires verifying current networking hardware and software systems work with your new SIP trunking system (meaning it will work just as smoothly for your vendors and customers, as well).

Selecting the Right SIP Trunking Provider

You now have enough foundational information to confidently choose the right SIP trunking options for your business. You don’t need to be a networking, IT, or telecommunications expert to enjoy the advantages of SIP technology, but with the right SIP provider, your company can prosper as though you are. can help. By plugging your communications network straight into a Tier-1 network, your business-wide SIP channels will be even more reliable than the landlines of yesteryear. It will also provide the redundancy, flexibility, and data protection you should expect when transitioning to professional SIP-trunking services – meaning greater efficiency and profits for your business.

Get started now by partnering with – you’ll receive dedicated and attentive support to walk you through the implementation process and further on as your business needs develop.

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