TelxTelecom Voice Over Ip

What is SIP Trunking?

SIP trunking is a VoIP service that uses session initiation protocol (SIP), the switching technology used in VoIP telephone systems, to allow users to initiate and receive communications and services between connected facilities, as long as there is a sufficient bandwidth available.

To illustrate, imagine a call center. Let’s say that our hypothetical call center needs to be able to make/receive X amount of concurrent calls during peak season. Using a traditional phone system, the center would have to determine that peak rate and then install the requisite number of T1 lines and channels to accommodate that volume, based on the primary rate interface (PRI).

Now, if that call center receives more calls than anticipated, in order to accommodate the load, they would need to add more channels, at an additional expense. Conversely, if they do not receive they anticipated number of concurrent calls, they pay to carry those unused lines.

Essentially, in a SIP trunk the internet replaces the traditional Public Switched Telephone Network (PSTN) trunk, removes the cost of dedicated lines, and allows the enterprise to communicate with a global audience at a fixed rate.


SIP trunking is a much more flexible solution that allows you to run your business more efficiently. SIP trunking is both dynamic and elastic, allowing you to run as many phones as you have people to answer them, and you only pay for what you use. As long as you have sufficient bandwidth, you can accommodate an unlimited number of calls.

Benefits of SIP Trunking

Reduced Costs

By routing voice communication over the internet, SIP trunking eliminates the need for certain hardware and services necessary to establish communication through the PTSN. Additionally, the hardware that is required is typically cheaper per line than the equivalent PTSN hardware.

Flexibility to Add New Lines

When the capacity of the PSTN gateway and/or PRI connection is reached, it is necessary to invest in additional gateways and connections, even for only one line. In a SIP trunk solution, the business can increase one line at a time, unless restricted by bandwidth, which would require upgrading the internet connection.

Increased Productivity

Introducing SIP-based real-time communication can impact how people collaborate across the organization. It is designed to facilitate all types of communication, including instant messaging, file transfer, application sharing, whiteboarding, video conferencing, and more!

Getting Started

In order to take advantage of SIP trunking, an enterprise must have a public branch exchange (PBX) that connects all end users, and internet telephone provider (like Telx Telecom) and a gateway that bridges the two.

VoIP’s negative reputation in the past was mostly due to poor internet connection. Depending on the quantity of phone calls, you may have to expand your data package to accommodate the bandwidth need for SIP trunks.

To learn more about SIP trunking and how it can work for your business, contact a Telx Telecom representative.