The Best SIP Trunking Providers for 2024

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• What is SIP Trunking?
• How SIP Trunking Works
• SIP Trunking Setup and Infrastructure
• SIP vs VoIP: What’s The Difference?
• SIP Trunking Pros and Cons
• How to Choose the Right SIP Trunking Provider
• SIP Trunking FAQs

 

What Is SIP Trunking?

SIP Trunking is a communications technology that enables users to make and receive phone calls and transmit other digital media over the Internet for real-time interactions. SIP Trunking supports cloud-based communications like voice over IP (VoIP) telephony, SMS texting, video conferencing, and messaging.

SIP Trunking uses Session Initiation Protocol (SIP) to establish a connection between endpoints, allowing users to stream data back and forth. A SIP Trunk is a single virtual phone line, not a physical device.

Businesses, residences, and individual users can use SIP Trunking from their choice of several endpoints: mobile applications, desktop-based softphones, or an on-premise phone system with physical VoIP and SIP-compatible phones.

SIP Trunking services are offered by SIP Trunking providers as well as some CPaaS providers, call center software vendors, and residential phone service providers.

 

How SIP Trunking Works

SIP Trunking uses the Session Initiation Protocol (SIP) to establish a live connection between internet endpoints so that users can stream VoIP calls, video conferencing, and messaging. Instead of traditional copper phone lines, SIP Trunking uses virtual SIP channels to connect users’ devices, called “endpoints”.

SIP provides instructions that help each endpoint coordinate a secure real-time media session. The protocol conveys each user’s IP address, the codecs used, and the types of data that will be streamed–such as audio and video packets.

SIP endpoint devices–like a VoIP phone, mobile app, or computer softphone–take the user’s analog (video or audio) signal and convert it into digital data, transmitting this data to all the other endpoints in the session. Each endpoint has a virtual SIP proxy server, which receives the data, securely converts it back to an analog signal, and delivers it to the end user.

 

SIP Trunking Setup and Infrastructure

Companies that want to use SIP Trunking for their business phone system have three main setup options: a cloud-hosted VoIP phone system, an on-premise system using an IP PBX, or converting your landline phone system into a VoIP-compatible system.

 

Cloud-Hosted SIP Provider

With a cloud-hosted PBX system, your VoIP provider hosts the SIP equipment and phone system in their data centers. As the end user, you don’t have to purchase any hardware–you only need an internet connection and a SIP-compatible device like a computer, mobile smartphone, or a VoIP phone.

Hosted SIP providers offer business VoIP software that users access through the internet. This software can include multiple communication channels like voice, SMS texting, video conferencing, and chat messaging. Multichannel UCaaS setups are becoming a popular option for businesses, with an expected 13.9% annual growth rate through 2032. Many hosted SIP providers also bundle advanced features in their software, such as routing capabilities like IVR and call queues, call analytics, and call monitoring.

An entirely hosted, cloud-based SIP Trunking infrastructure provides a cost-effective, low-maintenance option for companies seeking a virtual business phone system.

 

SIP Trunking with an On-site IP PBX

An onsite IP PBX system is a physical device that enables users in your office building to make VoIP calls using SIP. The IP PBX system includes a preset number of phone jacks, each connecting to one VoIP phone in your office building.

On-site IP PBX requires you to maintain the hardware, cables, and VoIP phones. It also limits scalability, since you can only run SIP lines to a predetermined number of users in the office. Still, this setup infrastructure provides greater control and privacy than using a hosted solution.

You can also purchase a virtual IP PBX server, which provides the same functionality as a physical IP PBX, but over the cloud. Virtual IP PBX software works well for remote companies with staff across the globe, who still want to provision SIP Trunking for all employees.

 

SIP Trunking with Legacy PBX

While legacy PBX systems typically make calls over the PSTN via copper-cable PRIs, you can use SIP Trunking to connect your legacy PBX to the Internet and facilitate VoIP.

This infrastructure requires you to purchase a session border controller (SBC) and analog telephone adapters (ATA), connecting these to your legacy PBX system. Then, on-premise users can use regular landline phones to transmit SIP data over the Internet.

SIP Trunking with a legacy PBX system is the most painstaking and inconvenient infrastructure since it requires the most hardware and maintenance. Further, this outdated option provides limited options for the features and communication channels you can integrate with your SIP Trunking system.

 

SIP vs VoIP: What’s The Difference?

SIP is an internet-based protocol that enables real-time media transmission, while VoIP is internet-based voice calling. Put simply, SIP enables VoIP calling. The two technologies work together, with VoIP using SIP.

SIP supports other real-time media communications besides VoIP. SIP also supports video, messaging, and other types of data transmission. The SIP protocol works harmoniously with other protocols, like real-time transport protocol (RTP) to enable VoIP. VoIP is one of the most popular software trends in the telecommunications space, with an anticipated 21.1% annual growth rate through 2031.

Voice over the Internet Protocol (VoIP) refers specifically to voice calls made over the Internet. VoIP calls rely on multiple protocols, SIP being one of them. Usually, VoIP utilizes SIP to establish calls, before using RTP for live data streaming during the call.

To learn more, read our detailed comparison of SIP vs VoIP.

 

SIP Trunking Pros and Cons

SIP Trunking offers many business benefits over a legacy phone system. A SIP Trunking phone system is cheaper, easier to manage, more scalable, offers better features and channels, and supports remote work. These benefits are one of the main reasons why the SIP Trunking market is expected to maintain a 10% annual growth rate through 2033.

On the other hand, SIP Trunking may require an upfront investment as you purchase new equipment or begin a new hosted software subscription. The process of choosing a provider and setting up the SIP Trunking system can also be frustrating, depending on your infrastructure.

Let’s take a closer look at the pros and cons of using SIP trunking for your business phone system:

 

How to Choose the Right SIP Trunking Provider

Your company’s SIP Trunking needs will vary depending on the equipment you currently have, the channels and phone system features you want, and your users’ locations. Depending on the provider you choose, the setup process will involve different steps. In this section, we’ll provide a quick outline, as well as a more detailed breakdown below.

A quick overview of how to set up your SIP system:

1. Determine if you want to repurpose any of your current hardware, like a landline PBX system or IP PBX
2. Compare providers and determine what additional equipment you may need
3. Work with your provider to purchase phone numbers and set up your account, IP, and routing information with SIP.

 

Here’s a more detailed breakdown of setting up your SIP Trunking infrastructure:

 

1. Determine Business Communication Goals

Before choosing a SIP provider and the equipment required, list the business goals you want to achieve with your SIP Trunking phone system. With more complex and multifaceted business needs, you will likely be better off with a hosted SIP Trunking solution or VoIP phone system.

Consider the following:

• Channels: Do you want voice calling only, or do you also want UCaaS capabilities like SMS texting, video conferencing, and internal team messaging? If you want multiple communication channels, you’re better off using an IP PBX system or a hosted solution for Trunking, rather than converting a legacy PBX infrastructure.
• Phone number needs: Do you only need phone numbers in your local area code, domestic numbers, or do you want international numbers? Do you want toll-free and vanity numbers? This answer will affect which provider you choose since each provider has unique phone number offerings.
• Routing: What are your routing needs for inbound calls? Do you plan to use an IVR menu, or simply route inbound calls to any available user? If your team has complicated routing needs and wants IVR, you may be better off opting for a virtual or IP PBX-based SIP Trunking solution, rather than converting to a legacy PBX system.
• Use cases: Do you plan to use your phone system for customer support, sales, or basic customer-facing communication? This answer will affect the routing tools, analytics, and sales campaign features you may want.
• Call volume: How many calls do you expect to make per day? During a standard business day, how many team members may simultaneously handle a phone call? These answers will determine if Elastic or Regular SIP Trunking offers more efficient pricing for your call volume.

 

2. Take Inventory of Your Current Setup

Consider the communications infrastructure you currently have in place, and which equipment you can repurpose for your SIP Trunking system. You may be able to reuse routers, VoIP phones, IP PBX systems, computers, and session border controllers (SBC) with most SIP providers.

You may also be able to repurpose a legacy PBX system for SIP Trunking, but this setup often requires additional hardware, like an analog telephone adapter (ATA) and SBC. These tools link your PSTN connection to the internet, enabling SIP. Converting a legacy landline system to SIP Trunking can be expensive and leave you with high-maintenance equipment. In most cases, you’re better off abandoning your legacy PSTN equipment and opting for a virtual SIP Trunking infrastructure, either with a physical IP PBX box or a hosted software setup.

 

3. Compare Providers

Once you’ve determined what equipment you may be able to repurpose, begin researching SIP Trunk providers, such as those on our list. Look for a system that accommodates your equipment and your business goals, while requiring minimal additional hardware.

Work with each provider to determine what your setup process may look like. Tell them the equipment you need, how many SIP Trunks or virtual lines you’ll require, and your communication goals. Get an idea of what your system would cost with each provider, and which VoIP or UCaaS capabilities each setup would provide.

When comparing SIP Trunk providers, consider the following:

• Pricing: Determine the cost of each SIP trunk (virtual phone line) with each provider. Many providers offer regular SIP Trunking charged monthly per line, and Elastic SIP Trunking that is charged per minute.
• Compatibility with your current setup: Speak with each provider, telling them about your current equipment. Determine if the provider’s offerings accommodate your equipment, if you’d need to purchase more hardware, and if your staff is up to the task. Many providers offer additional hardware and can assist with setup.
• Feature availability: Ask about the features that each provider’s SIP Trunking solution supports. Determine how easily you can set up features like a routing system with phone extensions, IVR menu, voicemail, call recording, and analytics.
• Phone number offerings: Learn about each provider’s phone number offerings, determining if they offer toll-free numbers, local numbers in your desired area codes, or international DID phone numbers.

 

4. Determine What Additional Equipment You May Need

When choosing a provider, be sure to communicate the details of your current infrastructure to get an in-depth picture of how your SIP Trunking setup process will look.

Ask your provider what additional hardware you may need:

• IP PBX systems–physical hardware or virtual
• VoIP phones and cables
• Analog telephone adapter (ATA) if converting a landline system
• Session border controller (SBC)

If choosing a software-based system or using an IP PBX, ask your provider if the setup requires any programming knowledge or an on-site developer. If you feel unprepared for any of these steps, ask if the provider offers any assistance with setup.

 

5. Work With Your Provider to Install SIP Trunking System

Since there’s so much variability between each company’s SIP Trunking setup needs, most SIP Trunking providers offer individualized installation support.

Establish a contact from your provider, who can walk you through each step of the process:

• Purchasing and installing hardware
• Purchasing and setting up SIP trunks
• Purchasing and registering phone numbers and assigning them to users
• Customizing extensions, routing, call controls, and IVR menus
• Customizing programming and code for any APIs, additional features, or integrations required
• Assisting agents or supervisors with using the new VoIP system’s interface and features

Although setting up SIP Trunking can feel overwhelming, a SIP system is generally low-maintenance once you get it set up. SIP Trunking providers offer 24/7 support over phone and email, to ensure your new system runs smoothly.

 

SIP Trunking FAQs

Below, we’ve answered a few of the most frequently asked questions about SIP Trunking.