What is SIP Trunking?

There’s no question that the onset of the internet has changed the world — especially the world of business communications. Phone systems that were once limited to copper wire connections now have the capability to connect via the internet. This progression of phone connections has allowed organizations to communicate better with customers, save money, and take advantage of the latest features — capabilities possible all because of SIP Trunking.

Sam Price, Product Manager at TelNet Worldwide, explains the details about SIP Trunking below. 

What is SIP Trunking?

SIP Trunking is a VoIP solution that utilizes signaling protocol to carry voice and data. The signaling protocol comes from “SIP,” which stands for session initiation protocol. SIP Trunking allows voice and data to be connected between two points in order to enable ‘cloud calling.’

This provides a connection between our session border controller through the Internet, to your PBX.

How SIP Trunking Works


SIP Trunking was created to evolve the needs of IP communications to support the features and call processing functions of the public switched telephone network (PSTN). To understand how SIP Trunking works, let’s compare it to a traditional phone call: When you conduct a phone call, you dial a number to reach someone. With SIP, you reach someone through a universal resource identifier or URI, instead of a traditional phone number, which will identify the call. 

A typical SIP call, as depicted below, will travel from a handset, through the PBX,  over an internet connection, to our data center switch, to the PSTN, to the call recipient. This all happens in seconds.

diagram of how sip trunking works

Find out more: What is SIP Calling? 

SIP vs. VoIP

There is a common misconception that there are differences between Voice over Internet Protocol (VoIP) and SIP. In actuality, you can think of VoIP as an overarching umbrella of telecommunications solutions, while SIP falls underneath that umbrella — so, think of SIP Trunking as a type of VoIP. 

SIP Trunking Features

SIP is very basic in technicality and very rich in functionality, with features such as:

  • E911 Service and Call Forwarding: E911, short for Enhanced 911, is a way to alert emergency services not only for help, but to direct them to your exact location as well  
  • Call Forwarding Busy: Redirects a call when there’s a busy signal 
  • Call Forwarding Always: Redirects all calls to a different number 
  • Call Forwarding No Answer: Redirects a call when there’s no answer
  • Call Forwarding Not Reachable: Redirects a call in case a phone number is unreachable 

Benefits of SIP Trunking

1. Cost Savings

With traditional wireline based services, such as Primary Rate Interface (PRI) for instance, you are purchasing 23 voice channels, when you may only need 12. This means that even if you’re only using a portion of your lines, you still are paying for all of them. With SIP Trunking, you can customize the number of lines for your business, which means you’re paying for exactly what you need and saving money.

2. Scalability

Whether you need to add 1 or 10 phone lines, SIP makes additional line installation simple and completely customizable. And as your company grows, we’ll configure additional SIP call paths on your existing Internet connection.

3. No Hardware

No longer do you have to worry about any bulky PRI equipment. With SIP, it’s totally cloud-based, so there isn’t any additional gear taking up space in your closet.  

4. Business Continuity

Built-in ‘Call Forward Unreachable,’ our business continuity feature, enables you to automatically redirect your calls to another phone or location in the event of severe weather, fire or a line cut, so business can continue no matter what. 

5. Unified Network

Manage your data and voice traffic over a single IP network with ease. Since SIP is a cloud-based solution, it’s easy to implement upgrades and new IP-based features across all your business locations.

6. 24/7 Monitoring

Wouldn’t it be nice to customize and monitor your SIP service at any time? Our SIP portal means that anyone with permission can see reports, perform routing, update E911 information, enable CNAM, and open tickets, all without the requirement of IT. 

Find out more: 7 Top Qualities to Look for in a Self-Service VoIP Portal

Getting SIP Trunking Service

Making the switch to SIP is easy, especially with an IP-PBX. If SIP trunking is a voice solution that would help make your business efficient, our team of experts will be there to assist you.

Related Articles:
10 Vital Things You Should Look For When Selecting a SIP Trunking Provider 
Our SIP Trunking is Mitel-Certified 

Lauren Bronston

Lauren is a Content Writer and SEO Specialist for TelNet Worldwide. When she’s not diving into data centers or SIP Trunking, Lauren writes TV scripts and builds music playlists for fun. Want to know more? Follow Lauren on LinkedIn.

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