improving your SIP trunking

SIP Trunking 101: The Fundamentals

What is SIP Trunking?

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, and it could reach 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 can 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. We want to clarify some of the fundamental aspects of SIP trunking without confusing industry jargon or unexplained acronyms.

First of all, SIP stands for Session Initiation Protocol. SIP trunking is a method of sending voice and other unified communications services over the internet. It works with an IP-enabled PBX (Private Branch eXchange). SIP trunking replaces traditional telephone lines.

SIP trunks 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.

Each SIP trunk supports SIP channels. A SIP channel is equivalent to one incoming or outgoing call. A SIP trunk can hold an unlimited number of channels, 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

The Difference Between SIP and VoIP and More Important Terms

There are a few terms to cover 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 obtain all benefits. However, it is essential to understand the basics of the technology.

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. It includes a group of protocol technologies, of which SIP is an example. SIP is one of the specific protocols that enable VoIP.

Voice Codecs

Codecs convert audio voice signals into compressed digital form 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 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 sacrifice of quality.

Carrier Tiers and Call Quality

Excellent audio quality is essential for any business communication system. The best solutions offer voice quality indistinguishable from traditional landlines, but it is crucial 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.

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 some things users consuming data will notice, but they can wreak havoc with voice calls. Enabling QoS ensures audio quality will remain high, even while data-intensive activities, like downloading large files or streaming content.

Related: What to Look For in a SIP Provider?

Why Choose SIP?

There are many benefits of SIP for your business. One of the most important is the reduced 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 grow at any time.

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?

Since SIP trunking is an active market, you may find several players in the industry. How to choose the best for your company? Check out these essential criteria:


A reputable partner will offer platform interoperability, meaning they can customize their services to your unique business communication needs versus offering a cookie-cutter approach.

Real-time data

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

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 toll fraud and hacking methods.

Bring your internet provider

Top suppliers will allow you to choose your internet provider, which will make the SIP trunking services available in as many locations as possible.


To ensure business continuity, ask about redundancy capabilities to seamlessly route calls in case of network failure. 

Customer service

Your SIP trunking platform should offer expert tech support.


Besides offering low-cost options to migrate to SIP trunking, industry leaders can directly configure their service to operate with almost any brand of IP-PBX or softphone. 

Carrier troubleshooting

The best SIP trunking providers will help you solve any carrier-related issues that may pop up. 

Free trial

Ask if your provider offers a free trial, so you can test the service to experience the benefits of SIP trunking first-hand before investing. 


Another criterion to verify is if they offer comprehensive SIP trunking training to you and any other stakeholders.


Evaluate the pricing model. Is it straightforward and transparent? Do you have to sign a lengthy contract? Do they charge a monthly fee or require you to make an upfront investment instead? Top partners will offer prepaid and no-contract services with affordable monthly payments per unlimited SIP trunk channel. You can then add or cancel channels at any time, as well as upgrade channels online with a simple control panel.


Check on the level of automation they offer. Are their implementation, monitoring and maintenance procedures remote and easy to manage? You want to reduce human intervention as much as possible.

With all of these basics covered, you have enough information to choose SIP trunking for your business confidently. Remember, you don’t need to be a networking, IT or telecommunications expert to take advantage of SIP for your company. By choosing as a partner, you will receive support to walk you through the implementation process and be there with you as the needs of your business change over time. Get started now!

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