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How do mobile phone category speeds work?

You may not realise it but your smartphone has been rated for a given phone category speed. But what does that actually mean in real-world usage?

The bevy of acronyms and jargon that surrounds smartphones can easily make your head spin. The odds are decent that the smartphone in your hand, pocket or purse is 4G enabled, but not all 4G phones are created equal. Yes, they do work across what are essentially 3 different networks in Australia, but the maximum speeds at which they’ll connect are determined by the quality of the radios within, and specifically which category of 4G LTE connectivity they support.

Within devices, speeds are fundamentally defined by the capabilities of the mobile modem (the radio bit that talks to the mobile network) within your device, which is given a "category" classification that directly relates to its maximum download and upload speeds.

That category, sometimes shortened to just Cat (plus the relevant number), will tell you a lot about how fast your device can theoretically go.

Here’s how the categories break down in speed terms:

CategoryDownload (Mbps)Upload (Mbps)Example devices
Cat 310050Apple iPhone 5
Cat 415050Apple iPhone 6, Samsung Galaxy S5
Cat 630050Apple iPhone 6s, Samsung Galaxy S6
Cat 945050Samsung Galaxy Note 7
Cat 1260050iPhone 8, iPhone 8 Plus, iPhone X
Cat 16100050Samsung Galaxy S8, Sony Xperia XZ Premium
Cat 181200150Galaxy S9, Galaxy S9+, Huawei P20 Pro

Just to confuse matters further, different models of the same phone sold in different markets worldwide feature different radio arrays, which means that they're classified with different categories. So for example, there's a model of the Samsung Galaxy Note 7 sold internationally which is Category 12, but the local model is a Category 9 device.

Depending on network configuration, some category sets may deliver the same download speeds (as happens with Category 9 and Category 10 for example) using different combinations of network aggregation.

In Australia, there are network differences that play in here as well. Generally speaking Telstra’s mobile network has been first to market with higher category devices, and this is definitely the case at the moment; it’s announced a Category 16 hotspot device due for commercial delivery in 2016.

Optus for its part does offer category 9 coverage, but currently only promotes that functionality for its network in selected parts of Newcastle and the CBD of Melbourne. Vodafone meanwhile uses its 850Mhz carrier aggregation to see its network peak at Category 6.

Above Category 4, you’re looking at telcos combining different mobile frequencies together to achieve higher phone category speeds, and that then depends on the actual spectrum holdings of a given telco in your specific location. Typically speaking, you’ll see the highest speeds from a given device in metropolitan areas, whereas once you start going regional you’ll slowly degrade down to lower speed 4G and 3G signal, or lose it completely if you’re genuinely remote. In those kinds of areas, your best bet for actual mobile coverage would be to use a satellite phone based solution.

I have a fast phone. How come I never get these kinds of speeds?

It’s very important to note that the given category of a phone’s connection refers to its theoretical maximum capability, but that’s different to the actual speeds you may encounter in real world usage. Even the best phones in the world can't break the laws of physics, after all. The most commonly used metaphor to demonstrate this is that of a busy highway, and we’re not going to mess with tradition, so here goes:

If a mobile network is a highway, your category speed refers to the maximum speed of your vehicle, or in this case smartphone. On a completely new road with no traffic at all you may get up to those speeds at good times. However, when it's congested because the network is a shared resource (same as the highway, for those keeping track of the metaphor) everyone’s speeds slow down. In extreme usage scenarios you may slow to a crawl, or not move data at all.

At the same time, the network conditions also play a role in your overall speed. To continue torturing the highway metaphor, it’s like having potholes or roadworks in the way, except for mobile networks those can be matters like being in an elevator, tunnel or simply having too many hills or buildings between you and the mobile tower.

Lower frequency signals have better travel characteristics than higher frequency ones but can carry less data, so most carriers bond channels together for the best possible mix, depending on their rights to different frequency spectrum areas. It’s a complex balancing game, much of which can be effectively invisible to you much of the time, but the practical upshot is that category speeds are always that notorious "up to" figure that you're unlikely to see in the real world. However, having a higher category phone on the right network can deliver serious speed benefits.

Can I upgrade my smartphone to a higher category?

The category classification of a given phone is essentially fixed, so it's not feasible to upgrade the software in order to gain a speed boost. The good news in this respect is that pretty much every smartphone currently sold or offered on contract in Australia should be cross-compatible with other networks, so if you do shift and keep your handset you should be able to enjoy the highest speeds offered by the carrier of your choice. If you do want to experience higher category speeds, however, you'll need to look into an entirely new handset.

If you're coming to Australia from overseas, or importing a phone, it's well worth checking its supported frequencies and category classification. This is easier than it used to be, with many phones offered in only a few "global" models, but you may find that a given overseas model is limited to slower speeds, or possibly only 3G connectivity within Australia due to frequency and/or category incompatibilities.

Get the highest Cat 9 speeds with these Galaxy S7 plans:


Image: Shutterstock

Alex Kidman

Alex Kidman is a multi-award-winning consumer technology journalist and the Tech & Telco Editor at finder.com.au. He's been writing about consumer technology topics for more than two decades, and enjoys breaking down complex topics into their component parts. He has written for just about every major Australian technology publication, and is a former editor of Gizmodo Australia, PC Mag Australia, and CNET.com.au.

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