SIP Trunking Basics

SIP trunking is a powerful telecom resource. This blog provides a refresher on SIP technology and its impact on enterprise communication.

August 25, 2021

What Is SIP Trunking?

Let’s start by covering a few definitions of key terms. SIP (session initiation protocol) is a communications protocol that enables multimedia communications over the Internet. SIP powers the voice, text, and video communications that we’re accustomed to using today.

SIP trunking connects a PBX (private branch exchange) phone system to the PSTN (public switched telephone network), allowing you to make the phone call. SIP is related to voice over Internet protocol (VoIP), but the two are not the same. While both protocols facilitate calling over the Internet, SIP can power additional communications modes such as texting and video interactions.

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Intrado offers SIP Trunking capabilities to its customers.


Benefits of SIP Trunking

SIP trunking provides several notable benefits that you’ll want to consider as you evaluate your telecom needs.

Scalable Call Capacity

The ability to quickly adjust calling capacity is crucial as call traffic ebbs and flows during different seasons, product launches, promotional campaigns, or emergency situations. With inbound SIP trunking, you get unlimited capacity for calls--meaning your phone system can support multiple calls at one time. Since there are fewer limitations or restrictions on call volume, it’s not necessary to plan capacity. With SIP, you can easily scale resources up or down to accommodate changes in call traffic.

Localized Numbers

Have you ever seen an incoming call from an area code that you don’t recognize? Chances are, you probably ignored that call. Whereas you likely would have answered the call if it came from a local area code. Sound familiar? When being able to connect with customers is essential, localized numbers can make a significant difference.

If your company has offices around the globe (or offices in different area codes), SIP trunking lets you create a number with a local area code for inbound and outbound calling. Creating a localized presence helps customers feel more comfortable engaging with your business. In addition, using SIP trunking can lead to better customer satisfaction because customers can communicate with your business using phone numbers that are familiar to them and less likely to be confused with spam.

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Enhance business calling from any location.


Dynamic Telecom Resources

Modern businesses' telecom needs are diverse, and a one-size-fits-all solution will no longer suffice. Calling capabilities are still essential, but it's equally important to have the ability to integrate other communications tools when needed. SIP trunking gives you access to a range of carrier-grade telecom resources to meet the needs of your customers and operations. An example of access includes configuring numbers to send and receive text messages and images and place video calls. You can also easily add new phone numbers and extensions and change call routing.


If you’re ready to move on from the unpredictable nature of hardware-based systems, SIP trunking can help. The protocol offers improved reliability because it takes potential hardware breakdown out of the equation. In addition, telecom security is an essential component of the overall reliability of your system. VoIP technology like SIP can make your business's calling more secure with the proper network security protections in place. For example, SIP providers send signaling and media to the PSTN in two separate streams, enhancing security and protecting the call audio. Some providers also offer a level of disaster recovery to help you protect your services if there’s an interruption like an Internet outage or other network impediment.

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Secure telecom resources and interactions.


Cost Savings

Not only does SIP trunking enable robust telecom capabilities, but it also improves your overall IT spend and eliminates the headache of routine hardware maintenance and upgrades. Since SIP trunking doesn’t require physical infrastructure, you don’t have to cover the ongoing costs of setup or updates over the life of the hardware. Further, because SIP trunks let you establish a local presence, you can engage with your global customer base without having to pay for long-distance calls.

Intrado SIP Trunking Solutions

If you’re interested in using SIP trunking for your business, Intrado offers two powerful solutions to meet your needs: OnSIP and Flowroute. OnSIP brings you the capabilities of a traditional phone system, including conference bridges, attendant menus, ring groups, and automatic call distribution queues. In addition, Intrado’s Flowroute solution enables inbound and outbound voice capabilities, as well as messaging. Flowroute also offers local, toll-free, and vanity phone numbers, as well as cloud-based local and toll-free international numbers. Read on for more details about each of these solutions.

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Optimize business communications with modern telecom resources. 



For those eager to get started with SIP trunking, OnSIP includes a range of hosted VoIP solutions that are simple to set up and easy to use, so you can get your calling up and running quickly. Customers also get a feature-rich hosted PBX solution without any IT infrastructure.

Through Intrado’s OnSIP, you can power remote working with free mobile and desktop apps that let you make and receive text or video calls from anywhere. In addition, you have the option to enable voice or video chat through your company's website whenever you want to add those communications components to your existing telecom toolbox.


Businesses that need to handle a significant amount of call traffic can rely on Intrado’s Flowroute solution, which allows you to make and receive an unlimited number of calls at once. If your call volume increases suddenly, Flowroute dynamically adds new routes to help you scale your voice services right away. As a result, there’s no need to wait to make infrastructure adjustments. Flowroute offers a pay-as-you-go model, so you only pay for what you use and can view your usage whenever you need to. In addition, Flowroute’s HyperNetwork™ helps customers sidestep interruptions by redirecting inbound calls that might incur service issues or outages.

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