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Monday 8 Jan 2024 | 5 min read

SIP Trunks: Your ultimate guide to your business internet phone service

A phone handset placed on a desk. In front of it is a computer keyboard and screen. Visible are two hands, one hand is typing on the computer keyboard and the other is holding the phone while typing on the dial pad.

Landline phones are still as important as ever for businesses.

As legacy phone systems get phased out in favour of IP Telephony (internet-based phone systems), it's decision time for businesses: With an assortment of different phone systems available, which one is best for your business? 

SIP Trunks could be the way to go if you've got a large office and rely on an extensive legacy phone system. SIP Trunking lets you convert your existing phone system to one that supports Voice over IP (VoIP) - the new standard in business phone systems. 

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In this article, you'll discover what SIP trunks are and how they can help your business.

What is a SIP trunk?

SIP trunking allows your business to send and receive local or long-distance phone calls over the internet. SIP Trunks convert a copper-driven phone line to VoIP, delivered via high-speed internet.  

SIP trunking uses an on-site PBX server to route incoming calls through virtual channels. A SIP trunk channel is a virtual version of a traditional phone line. Your business will need one SIP trunk channel for each simultaneous call. 

Diagram demonstrating how a SIP trunk works

As legacy phone systems become redundant, SIP trunking is a convenient solution that uses your existing phone infrastructure. With SIP Trunks, you can access the advanced features and reduced costs of VoIP while keeping your current phone system. 

SIP Trunks vs Hosted PBX: What's the best VoIP phone system for a small business? 

The benefits of SIP trunks

Whether you’re running a call centre or help desk, use your phone system for inbound and outbound sales, or simply need to improve communication in your business, SIP trunking comes with many benefits. 

Cost Savings

Using SIP trunks will save your business money by removing the traditional line rental fees for your phone system. And, by delivering calls through VoIP, the cost of the phone calls is substantially reduced. 

Aussie Broadband offers a premium SIP Trunk service that provides businesses with free local, national, and mobile calls from just $60/month (per channel). If your business spends a lot of time on the phones, that can result in massive savings. 


With SIP trunks, you can quickly and easily add new numbers to your phone system as needed. Previously, this would have been a complex task requiring changes to your physical infrastructure. 


Unsurprisingly, given it's the new standard, VoIP is the most reliable voice technology available. And a full fibre internet connection, available through a $0* upgrade to high-speed Fibre to the Premises, takes it to a whole new level.  

Access to analytics and insight 

With better data, you can make better decisions. And if phones are a big part of your business, SIP trunks let you access metrics that can help you optimise your business processes. 

Say you want to know the length of a typical phone call, or the average call volume at certain times of the day. SIP trunks take out the guesswork (or manual work) in collecting this information. With real-time data right in front of you, you can resource your business phones (and the people behind them) in a way that maximises efficiency and effectiveness. 

Install without disrupting business activity

Businesses often hesitate to upgrade their phone infrastructure due to the potential for downtime disrupting normal business operations. 

That's why SIP Trunks are a popular choice for businesses that rely on their phone system. They're a turn-key solution to modernising and upgrading your phone system. 

In most cases, installing a SIP trunk won't disrupt your business, since you can keep your existing phone system and numbers. 

Enables a remote workforce

Another important benefit of SIP trunks is that they support your remote workers.  

With hybrid working models now standard, phone systems stuck in the office aren't practical anymore. In a hybrid working environment, an IP phone system that works from anywhere is critical to enabling an effective workforce. 

With a SIP trunk, you can set up automatic call forwarding to send calls to any phone system outside the office (such as a mobile number). 

You can also set up softphone capability, so your employees can make and receive calls on your phone system via a softphone app they can use on their mobile phone or computer. 

SIP Trunk vs Hosted PBX - How are they different?

While SIP Trunks and Hosted PBX phone systems operate through VoIP technology, they work differently. 

SIP trunks convert traditional phone lines to VoIP, while hosted PBX phone systems operate entirely online via cloud technology. 

So, the result is much the same: Through either SIP Trunks or Hosted PBX, you'll be able to access the benefits of VoIP. It's just a matter of whether you want to keep using your current infrastructure. 

Which phone systems are compatible with SIP Trunks?

Most newer PBX systems are compatible with SIP. Although, SIP Trunks aren't automatically compatible with some older PBX systems. If your phone system isn't compatible with SIP Trunks, you can use an ATA Analogue to VoIP Adapter to make it work. 

Customise your SIP Trunk solution

Want to modernise your business phone system with SIP Trunks? Visit our SIP Trunks page to find out more about our SIP trunking services and pricing for voice and data packages. When there, you can get clarity on how much it'll cost based on your business needs through our voice plan builder. 

After entering your business address to see what connection you can get, choose from standard (pay-as-you-go calling) or premium (unlimited local, national and mobile calls). Then, select how many SIP lines (phone lines) you'll need. 

Then, if you need an analogue telephone adapter and a dedicated internet connection for your phone lines, you can choose to add them. Not sure if you'll need these for your phone system? Contact our team of business phone experts for a free consultation. 

Once you've customised your phone system, you'll receive an instant quote. 

If you want to learn more about SIP Trunks, or get guidance on your business's ideal telco solution, speak to our Australian-based business experts. Give our 100% Australian-based team a call on 1300 480 905. Or, if you prefer, get in contact via our website. 

Tags:BusinessHosted PBXPhone systems

Written by

Michael Hayman Headshot

Michael Hayman

Content Writer

Michael is Aussie Broadband's marketing copywriter. Michael has worked as a content marketer since 2016, predominantly in the B2B space. He is passionate about writing educational content that helps small and medium businesses run, grow and...

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