Review: CAT S31 is an entry-level smartphone with military-grade toughness

Mar. 22, 2018 12:02PM EST

As I discovered recently with the CAT S41, tough phones designed for a specific purpose are surprisingly good. They won't win any beauty competitions compared to the likes of the iPhone X and Samsung Galaxy S9, but where those handsets would cringe at the very sight of a construction site, an archaeological dig, or a tradesman's toolbox, CAT phones are designed to shrug off tough environments.

Up next, I have the $330 CAT S31. Smaller and cheaper than the S41, this is a similarly robust-looking handset, but one which trades a degree of toughness for a more pocket-friendly design.

CAT S31 review: Design

As I just said, the S31 is more compact than the S41 and, as a result, less imposing. It doesn't shout quite so loudly about its ability, but still possesses an aesthetic that means business. Looking like it is already wearing a protective case, the S31 has a rubberized body designed to brush off even the most serious of knocks and drops.

CAT claims the S31 is IP68 certified - just like the S41 - and can survive being in 1.2 meters of water for 35 minutes. This means more water resistance than most smartphones, but it lags slightly behind the S41, which can survive for 60 minutes at a depth of 2 meters. Both phones cover their headphone jack, micro USB port, SIM, and microSD card slots with rubber seals.

Just like the S41, the S31 meets the Mil-Spec 810G military standard, meaning it can withstand a 1.8-meter drop onto concrete.

The CAT features a rugged, rubberized body built to military standardsGearBrain

Where the S41's body features hard plastic with a rubberized back, the S31 is rubber all over, making it a little softer to hold. Curved edges also attempt to make the S31 more 'normal,' but in my experience, this meant it was more likely to slip out of my hand. For this reason I prefer the flat edges of the larger model.

Physical keys replace Android's on-screen home, back, and multitasking buttons. They feel good enough, but lack the more tactile click of those on the S41. The S31 sometimes feel a bit mushy and less precise, but are still more affirmative than a touch screen - and of course they work with dirty, wet, or gloved fingers.

Speaking of buttons, the S31 has an extra one on its left side which be configured to do whatever you want. For example, you can assign a short press to answer incoming calls and a long press to turn on the phone's flashlight or open any installed app.

CAT S31 review: Display

The CAT S31 has a 4.7-inch display with an HD resolution of 720 x 1280. For 2018, this is a fairly low pixel count and means there is a small amount of fuzziness to Android's otherwise sharp graphical edges.

Although such a resolution would surely spark riots among smartphone fans if it were found on a new Galaxy or iPhone, here it matters far less. That said, the display's blacks aren't as good as I'd like, and the screen picks up a lot of fingerprints.

Physical buttons are welcome but not as tactile as we would likeGearBrain

The S31 is about being tough and functional first, with aesthetics of less importance. What matters more is that the display is large enough and bright enough, with acceptable contrast and viewing angles. It is covered by Corning Gorilla Glass 3, compared to the S41's Gorilla Glass 5, but also comes with a factory-fitted screen protector.

Adding further protection is how the S31's body creates a raised lip around the display, preventing it from coming into contact with flat surfaces when dropped screen-first.

CAT S31 review: Cameras

The S31 has an 8-megapixel camera on the back and a 2-megapixel camera on the front. These are not great stats, and when using the S32 it shows. You're not going to shoot award-winning photos with this phone, and anyone who receives your selfies will notice their grainy texture and poor exposure.

On a regular smartphone, this would be a major disappointment - even one priced the same as the $330 S31 - but it's clear that CAT, and manufacturer Bullitt, has focused on spending money elsewhere. That, and I suspect making low-volume, specialist phones like these reduces the economies of scale and prevents manufacturers from buying better components at an affordable price.

That said, the S31 can take acceptable photos, so if you need basic images of the construction site you work on, you'll be fine.

CAT S31 review: Software and performance

CAT has made the sensible decision to keep Android 7.0 Nougat almost entirely standard on the S31. This means no bloatware, no pointlessly duplicated apps (I'm looking at you, Samsung), and an operating system that is simple and fast. The S31 is powered by a quad-core Snapdragon 210 processor, as used by a wide range of budget smartphones from LG, Acer, Alcatel, Huawei, and ZTE.

The eight megapixel rear and two megapixel front cameras are adequate but not all that impressiveGearBrain

It has 2GB of RAM, 16GB of storage, and acceptable performance. If you use an iPhone, Samsung Galaxy or Google Pixel in your private life and have been given a CAT S31 for use at work, then you are certainly going to notice the difference. But you're unlikely to be playing intense 3D games while demolishing a building or fixing someone's boiler, so it shouldn't get in the way of what the phone is designed for.

I tried out PlayerUnknown's Battlegrounds - exactly the kind of intense, 3D, multiplayer game the S31 shouldn't have to deal with - and, sure enough, it was very slow to load and then failed to work properly. The similarly demanding Real Racing 3 by EA also took a long time to load, but played surprisingly well. Simpler games like Stack load quickly and play smoothly. A large 4,000mAh battery means the occasional game session shouldn't stop the phone from surviving a full day of work.

CAT has added a few apps of its own, but these are more like shortcuts to content online and in the Google Play Store than actual applications. One, called App Toolbox, opens a store page full of apps a CAT smartphone owner might find useful, such as spirit levels and specialist calculators.

CAT S31 review: Verdict

Like their sleeker, pricier, and more desirable counterparts, tough phones come in all shapes and sizes. The CAT S31 is at the cheaper, simpler end of the scale, lacking the performance of the more expensive S41 but almost matching it in terms of toughness.

If you need a tough phone for work - or are looking to buy them for your employees - but don't require much in the way of performance, the S31 is worth looking at. It can handle email, web browsing, photography, and useful apps aimed at use in the construction site. It lets you bring smartphone functionality to hostile environments, but is unlikely to be your one-and-only handset.

S31 buyers will appreciate the rugged design, but they'll be glad to get back to their iPhone, Galaxy or Pixel when they finish work for the day. Where the CAT S41 is arguably a capable smartphone in its own right, the cheaper S31's performance limitations mean it will probably spend its nights in your toolbox or van, not on your bedside table.

Pros:

Water resistance and military-grade toughness
More compact than the large CAT S41
Large battery

Cons:

Middling performance
Display has Gorilla Glass 3, not 5
Not as secure to hold as the square S41