SIP Trunks – an Idiot’s Guide to Understanding Them

Businesses are looking for ways to cut costs or enhance revenue in a competitive economic environment. One way you can do that is by using SIP trunks. You’ve probably heard terms like hosted VoIP or SIP trunking and wondered what it all meant. You might be curious about the new technology but lack the knowledge to make the decision to switch. Before you rush to get rid of your current phone system, take a moment to find out all you can about the alternatives.

What is SIP Trunking?

SIP trunks are a modern alternative to ISDN lines that most organizations use to make phone calls. The most common way for an organization to connect to the Public Switched Telephone Network or PSTN was through a PBX or private branch exchange. This allows a company to allocate phone lines and numbers among hundreds or thousands of employees.

SIP trunking lets you do the same thing but it is cheaper and more efficient. SIP trunks route voice calls over the Internet, just like how images, sound and documents  travel over the Internet. It means you don’t have to maintain two separate networks, one for data and another one for phone calls.

What Does SIP Stand for?

Before we look at SIP trunking and what it can do for your business, you should know the basics. SIP stands for Session Initiation Protocol and is an IP standard established by the Internet Engineering Task Force. Although there are many other protocols that can be used for VoIP, SIP is the most common and widely used.

SIP is a text-based protocol and it is very similar to how HTTP operates. HTTP is the basic protocol which is the basis for webpages. SIP controls how a session is initiated, set up and terminated. When you make a VoIP call, SIP establishes the connection between the users. For landlines, a session simply consists of voice signals. With SIP, you can send voice, pictures, video, documents and other forms of media.

What Are SIP Trunks?

On the PSTN network, a trunk referred to a bundle of lines that are shared among a group of users. The term ‘trunks’ doesn’t actually apply to SIP-based communications since there are no physical wires or connections. However, the term is used within the VoIP industry and widely accepted.

SIP trunks also connect an organization with the external world but do so over the Internet or other data networks. Once you switch to SIP trunks, most calls will never touch the PSTN at any point. Unlike older PRI lines which you could only purchase in bundles of 24 or 32, SIP trunks can handle smaller increments. In the past, if you needed 26 lines, you had to purchase 48. Most SIP trunk vendors will allow you to purchase exactly the number of lines you need and sometimes you can handle extra volume simply by increasing the available bandwidth.

How to Deploy SIP Trunks?

There are two ways to deploy SIP trunks – centralized or decentralized. In a centralized configuration, you can direct all phone calls to a single location (typically headquarters). The company connects to the ITSP through SIP trunks from this place. This type of deployment is easy to manage and implement. But it does mean that if there is a problem with the SIP trunk, all offices lose voice communication. In other words, you have a single point of failure.

In a decentralized configuration, each office has its own SIP trunk. A problem at one location doesn’t bring down your entire organization. However, it also means you have to purchase software and equipment at all offices which can become expensive. It also takes more maintenance and planning to deploy.

How Can SIP Trunks Help Your Business?

When you switch to SIP trunking, phone calls travel over the Internet similar to other forms of media. So just like how you don’t have to pay for each individual email you send to a colleague, calls made between employees in your company are free. It doesn’t matter if they’re located in different offices or one of them is working from home. Long-distance calls become much cheaper since the call travels over the PSTN for a short distance.

You eliminate maintenance costs for two different networks that essentially serve the same purpose. You can send video, instant messages and voice calls through the same system instead of using different software for each. You can bring together different services like digital faxing, voicemail, IVR etc in one neat package. You can even integrate SIP trunks with other enterprise software like CRM and ERP systems, greatly improving productivity.

Upgrading to SIP trunks can be one of the smartest decisions you can make for your business today. Just make sure to do your research before upgrading and start seeing benefits almost immediately!