How Does SIP Trunking Work & What is It – Fully Explained

November 18, 2020by Russell0

As a business owner, you are looking for a solution that can cut your costs and spending. You do not know each and everything to boost your VoIP business or business phone systems. I assume that you heard something good about SIP trunking.

 You may also hear that some of your business friends are doing great with it. But you want to know more about SIP trunking.  You also need to know how to SIP Trunking works before contacting a SIP trunking provider.

If you want to revolutionize your business to take a giant leap, SIP trunking can perform a great role. It will help you in upgrading your PBX to an internet-powered phone system. From a crisp calling system to high video calling, no one wants to risk their reputation. Using SIP trunking allows you to lessen your dependency on hardware. 

As SIP trunking is affordable in price, any business can benefit if they know How SIP trunking works. 

What is SIP Trunking?

A SIP trunk is the most efficient virtual version of an analog telephony system. Using SIP trunks, a VoIP SIP provider can connect many calling channels to your PBX. It allows you to make long-distance calls. You can do both internal and international calls over the internet protocol (IP).

SIP is the short form of Session Internet Protocol. It is an application layer protocol for many real-time applications. SIP is the way you achieve a VoIP (Voice Over Internet Protocol) call. You can go for initiating, maintaining, and terminating real-time sessions. That includes voice, video, and messaging applications. 

Trunking is the backbone of a telephony system. It connects many calls or phone lines to a telephone network. SIP trunking is an efficient and reliable trunking alternative to conventional PRI trunks. It is also cost-effective.

If you understand how SIP trunking works, you can connect one or more channels to the IP-enabled (PBX). Here PBX means private branch exchange. By using a SIP trunk, it is very convenient to make outbound calls on your existing system. You don’t need to compromise without restrictions on the number of concurrent calls. 

As it is a VoIP Softswitch solution, SIP trunking replaces PSTN to reduce your costs. PSTN stands for Public Switched Telephone Network.

How Does SIP Trunking Work

Are you excited to know how SIP trunking works? What is the architectural structure of SIP trunking? Let us know. We are going to prepare a complete explanation of how SIP Trunking works.

You also need to learn about the SIP trunking architecture.

Applications of SIP Trunking

The main application of SIP trunking is to replace traditional PRI technology. In the field of telecommunication, PRI has been used to send voice and data. Primary Rate Interface uses hardware components i.e, copper wires.

With SIP trunking, VoIP technology can transfer voice and data. Along with instant messaging, you can send bulk SMS service. Not only that, now it’s easy to do video conferencing without any hassle.

SIP trunking is the right tool for any telephone business. Anyone can upgrade its telephony system at a minimal cost. The major applications of SIP trunking are as follows:

Video conferencing

Voice conversation

Streaming all kinds of media

Web conferencing

Desktop sharing

Inbound and outbound calls

In short, You can use SIP trunking for:

  • Setting up calls
  • Controlling many calls
  • Making outbound calls, and
  • Managing a call management system using calling cards.

As it’s flexible and quite lightweight, you can provide VoIP connectivity. It only requires PBX without taking extra pressure.

Benefits of Using SIP Trunking

Cost-Effective – SIP trunking is very cost-effective and budget-friendly. You will get a lower monthly fee to have many phone lines compared to other trunking solutions. The cost of Direct Inward Dialing (DID) is also low. As there are many SIP Trunk providers in the market, they did the competition to drop down the call charges.

Based on different service providers, the cost of international charges is also low.  Doesn’t sound great?

SIP trunking supports greater call densities than PRIs. Compared to PRI, you can use more than 50 concurrent calls without impacting the quality. PRI supports only 23 concurrent calls.

Flexible and Scalable – Everyone wants to expand their business and its growth. Suppose you have massive increases in calls and other telephony services. What should you do? Do you ask the customer service to set up new hardware and enable new lines?

Before the use of SIP Trunking, people had to do it. SIP trunking is scalable and flexible to any kind of business. There is no need for physical installation. You don’t need to set up even with unlimited channels per trunk. You can add and enable new channels within hours.

As it is flexible, you can use the same phone from anywhere in the world.  For this, you can use telephone number mapping, or ENUM (E.164 Number to URI Mapping). In fact, most of the SIP trunking providers allow you to use phone migrating without any cost.

Disaster Friendly: Traditional telephony service can be disrupted due to phone failures. Bad weather or a damaged telephone pole can be also responsible.

Luckily, SIP trunking with VoIP boasts higher reliability. This means that you can keep using your phones even in case of failures. Calls can be routed to other lines, offices, or your mobile device.

You can keep your business going smoothly and interruption-free.

Better customer service – Provide better customer service by adding more geographical numbers. Quickly and easily add numbers to your SIP Trunk.  And, end them on your IP PBX. You can give customers more options to dial in at a significantly lower cost, even long distance. Customers can contact you more easily, and sales will increase.

Cut VoIP Gateways – SIP Trunks will cut the need to buy and manage VoIP Gateways. All phone calls that come in via internet protocol do not need any extra conversion. It ensures quality by eliminating VoIP gateways.

Leverage a modern IP PBX – With the help of SIP trunking, leveraging modern IP PBX is now at hand. It is easier to connect an IP PBX to SIP Trunks than PSTN. You can now use it to increase productivity and mobility and boost your business’s sales.

SIP Trunking vs VoIP

The difference between SIP Trunking vs VoIP is the capability of file transferring. VoIP can send only voice data over internet protocol. But SIP trunking can send all kinds of digital media including voice and video.

Another difference between SIP trunking vs VoIP is the medium in which they operate. VoIP depends on the internal private network to communicate with other networks. But, SIP trunking can use any network. It includes VPN, internet, or ISDN (Physical Phone Network) to transfer data.

VoIP hosts can filter and traffic from one centralized network. They can also organize and send voice data. But, SIP Trunking uses peer to peer to file transferring method that can handle a large amount of data at a time. This is how SIP trunking works to enhance the file transfer capabilities.

SIP trunking needs only a modem to transfer data. But VoIP needs to connect required headsets.  Other devices connected with the computer to make it workable.

Cost of SIP Trunking

The cost of implementing SIP trunking varies depending on your business needs. Yet, the usual cost to setup SIP trunking is between $0-$150, and the monthly costs can be around $25-$50 per trunk.

Some SIP trunk providers provide unlimited inbound and outbound calls. You can call both locally and internationally based on per channel or call basis. Depending on your needs, you can increase the limit of your channel. For this, contact your service provider. You can use hardware components i.e, copper wires. 


I'm Russell, our go-to expert for VOIP softswitch server installation. With hands-on experience in deploying Sippy Softswitch, MVTS Pro, iTel Switch, and MediaCore Softswitch, he's the guru you can rely on. As a key contributor to, Russell simplifies the complexities of server setup, configuration, and troubleshooting, making the world of Voice over IP accessible to all.

Leave a Reply

Your email address will not be published. Required fields are marked *

VPSVOS Communications is a registered company in the United States of America. Registered Office: 19854 Michigan Avenue Brekford, CA 599780 USA.
OUR LOCATIONSWhere to find us?
Stay up to date with the latest news about VPSVOS Communication, events, special offers and more by connecting with our social media.
VPSVOS Communications is a registered company in the United States of America. Registered Office: 19854 Michigan Avenue Brekford, CA 599780 USA.
OUR LOCATIONSWhere to find us?
Stay up to date with the latest news about VPSVOS Communication, events, special offers and more by connecting with our social media.

Copyright © 2005 – 2024 VPSVOS All Rights Reserved.

Copyright © 2011 – 2024 VPSVOS All Rights Reserved.