How do phone calls get to Australia? Monday 01 July 2019 @ 17:14

You might work in telco every day, but have you ever wondered how phone calls actually reach Australia? It seems so seamless on the surface, but there’s much more to it than you might think. Australians receive calls from various countries across the globe every day, whether it’s family, friends or colleagues. Despite this, the process of how international calls get to us is still a mystery to most people. We’re here to explain how it all works using the example of Symbio’s global voice network.

Domestic vs International Calls
Here at Symbio, we’re a carrier in our own right – one of only four voice carriers in Australia – and operate the largest IP voice network in the country. This allows us to provide IP voice carriage services and software to all levels of the telco industry, while also delivering complete, in-country coverage.

Symbio, like other Australian carriers, maintains an up to date register of all Australian numbers by reading the ACMA directory as well as the porting registers of all Australian carriers. When a call is placed domestically, Symbio automatically figures out where to send the call based off this information.


For international calls, however, this can’t happen, as an international carrier doesn’t have knowledge of Australia’s numbers. So, this begs the question – how does someone calling Australia from overseas actually end up getting connected to the right person?

International calls, easily explained

The telecommunications industry doesn’t just revolve around wires, networks and cables. A lot of how phone calls happen, especially internationally, is all about mutually beneficial relationships established between providers in two different countries. International transit carriers (ITCs) are the ones who help act as the bridge between the country that the call is coming from and Australia. In order to play the part of this ‘middleman’, they must have a relationship with both the ‘caller’ and the ‘receiver’.

Let’s say for instance that somebody in India was calling somebody in Australia from a mobile phone. The call would go from that person’s phone in India to their mobile network, who would then direct the call to that mobile network’s designated international carrier for Australia. The ITC then sends the call onto a company who specialises in direct interconnects – such as TNZI, MNF Group’s international voice arm – who ultimately directs the call to Australia via Symbio, who then sends the call onto the recipient.

The advantages of using VoIP

In addition to end-to-end control of our own VoIP network, we have relationships with local carriers in various countries all over the world. This allows us more control over both the caller ID and the call path, which in turn enhances both the security and the quality of the call. To complement this even further, our Global Routing System means calls are delivered at the best quality by the most efficient route.

Using IP to route calls isn’t just valuable for commercial reasons, though. As opposed to the traditional PSTN copper network, VoIP technology gives all of our calls great resiliency. Using the Internet for routing means that it’s highly redundant, so customers can get the naturally added advantages of an IP-based network, along with failsafe availability if needed and Tier 1 service level commitments.

Now you know how international calls get to Australia, why not explore Symbio’s solutions for global carriers

Get in touch with us today to set up a chat with the team.