S31 CAT Construction Phone Review

CAT S31 Rugged Smartphone

Not too long ago, when I went to work at commercial constructions sites, one of the first things I put on with my high visibility vest was a job site two-way radio. These communication systems were job specific with a set of crystals that enabled all of the radios to communicate together on a dedicated frequency.

I could drop these radios, get them wet in the rain and bang them into walls or job boxes. They ‘took an licking and kept on ticking.’

The S31 CAT Rugged Smartphone is the modern day equivalent to these rugged radios.

Today, commercial contractors and workers use smartphones in place of radios. The industry is more efficient with these modern phone products as communications and information transfers are reliable and fast. Communication overall is enhanced and you have the added benefit of searches via Internet. However, one big problem is very evident and stems from a simple fact. The rigors and hazards in a construction site are simply greater than the durability and ruggedness of most smartphones.

On a recent project of mine, I asked a group of workers about their experiences with smartphones while doing earth moving, concrete and excavation work. Their tales and tribulations with smartphones in this technology-hostile environment were not only humorous and entertaining but the group, on average, had broken, seriously compromised or replaced one to three devices, each, within the last year.

Site work seems to be especially brutal on smartphones. While my sampling of workers was not statistically large, the number of these site work personnel that had replaced or were carrying around bandaged, damaged or broken phones struck me as a very large percentage.

Bringing Durability to Modern Technology

That is when I took out my S31 CAT Rugged Smartphone. Because they were a group of site contractors, they first wanted to know where I had purchased a CAT cover and CAT screensaver for my phone and how could they buy them. They loved the CAT branding.

Without answering them, I purposefully tossed my S31 into a two-foot deep muddy puddle of water next to us. They thought I had lost my mind, until I pulled the wet phone out and showed them that it still worked.  My S31 was passed around the group, who repeatedly dunked, dried off and passed around to the next guy to dunk it.

Another trip in the puddle for the S31 Rugged Smartphone

Besides the ability to withstand drops and water, the group made comments about the screen brightness on the sunny day, the easy-grip case design and scratch-free glass.

Keeps on Ticking

Of course, I had even more fun amazing them when I showed them how the screen works with gloves on.

If I had some S31 phones with me, I could have sold 18 of them on the spot.

The S31

The engineers at CAT worked hard with their manufacturer to produce a phone that is suitable for the construction environment. The S31 meets or exceeds the IP68 certification and MIL-SPEC 810G requirements. In practical terms, this means that the S31 is dustproof and waterproof at 1.2m (4 ft) water depth for up to 35 minutes of immersion and is fall-proof from heights of up to 1.8m (6 ft).

With a diagonal screen size of 4.7 inches, the S31 is a relatively small form factor. I like this size for the construction environment because it easily fits into and retrieved from my pants or vest pockets. I agree with the site work guys and like the ribs and easy to grip features of the case. It is great to have a phone with an integral case that is custom-fitted at manufacture and rugged enough for construction.

Technical Stuff

From a technical perspective, the S31 works on a wide variety of cellular networks. The phone is unlocked when sold. In my case, I simply inserted the SIM card from an old iPhone into the slot and I was up and running on my AT&T network.

The S31 has a Qualcomm Snapdragon 210 MSM8909 processor with the Adreno 304 graphics engine. The S31 has 2GB of memory and 16GB of flash memory. These technical features place the processing speed of the S31 in the mid-range of most smartphone performance. This may not be the best phone on which to play graphic intensive games or applications. However, I found the performance of the S31 very suitable for the construction and communication apps that I put on and used with the S31.

The S31 has both a memory and SIM-card slot on the right hand side of the phone and tight-fitting flaps protect the environment seals for these slots. Users can put in up to 128MB of additional memory in the expansion slot and seal in the memory card with a flap.

Speaking of flaps, the S31 has a feature that reminds me to close the flap on the charging port when I neglect to do so after removing the micro-USB cable.

With an 8 MP main and 2MP front camera, the S31 has less resolution than the top-of-the-line smartphones that may have 12 MP and 8 MP, respectively, in today’s offerings. As a web-cam, the 2MP front camera performance is lacking in picture quality. In my experience, the 8 MP camera is sufficient for the photographic needs on the construction site.

Especially outdoors, the S31’s 1280 x 720 screen visibility is excellent. Screen content is bright, clear and visible any screen angle. The S-31 screen is a super star in outside bright conditions and is superior to any other smart phone screen I have used.

As a phone, I was impressed with the call quality and I especially liked the S31 speaker for hands-free talking. The speaker volume is very loud and sufficient for all but the loudest construction noise.

One S31 feature that I liked a lot is the assignable free key. I used this key to open the camera app directly with a short click and to open the phone app with an extended click. The operating system allows others to choose from a list of over 38 apps (limited by my specific number of apps) on the phone to enable with the key.

Finally, I like the duration of the battery life. I tested the battery life with a wireless LAN with the display switched on and an active browser application opened. The battery lasted over 17 hours and 34 minutes for this test. Additionally, CAT indicates that standby time for the S31 is around 38 days.

The S31 Rugged Smartphone– How I like It

The S31 represented a different type of smartphone for me. Full disclosure – I have been an iPhone user from the first introduction of that product. As a result, the Android operating system was a real departure from the iOS that I know well. My learning curve for the S31 was steeper than I would have liked. I attribute that steepness to the difference in my experience with the two operating systems. As time had gone on, I am now operating system-bilingual. There are features that I found and like about the Android OS. I really like the feature of keeping the phone unlocked while it is in my hand or pocket. (Uses a lot more battery but is ready to go when I need it.) And there are other features of the Apple operating system that I like.

The S31 smartphone can be purchased from the CAT website for a price of $329.99.  Search www.catphones.com. In this day of $1,000 smartphones, the S31 represents an excellent value for a ruggedized smartphone. A visitor will see other CAT smartphones with additional capabilities in addition to the S31.

My bottom line on the S31 is that it is a perfect match for what I need in my construction environment.

Outstanding features

  • Robust Easy Grip Case
  • Water and Dust Proof
  • Gorilla Glass Screen
  • High Visibility and Brightness in Daylight Conditions
  • Gloved-hand Operation
  • Impact Resistance
  • Memory Expansion Slot
  • Assignable Free Key

Areas Needing Improvement:

  • Enhanced processor performance
  • Higher Resolution Cameras


Smartphone survival on a construction site is a real issue as these devices are operating in an unforgiving environment. Luckily, CAT can offer a solution.

I think the S-31 is a perfect match for my needs on the construction site and for what I do. It is a great utility device for my communication and information field needs.

The S31 is a ruggedized phone that is suited for these conditions. While no phone is indestructible, the CAT S-31 proves to be the device that CAT promises. Carrying on Caterpillar’s leading heritage of supplying tough, reliable equipment for rugged conditions, the S31 is a rugged smartphone that can cope in the construction world.

Highlighted CAT S31 Features and Specs

  • Powerful 4000 mAh non-removable Lithium Ion battery provides up to 38 days standby time and 15 hours of 3G Talk time
  • IP68 certified waterproof up to 1.2 meters (3.9 feet) for 35 mins; military standard 810G shock and drop proof up to 1.8 meters (6 feet); scratch-resistant Corning Gorilla glass 3 screen
  • Super bright 4.7” HD 720 x 1280 display can be read in direct sunlight and used when wet or with gloved hands
  • 8MP Autofocus rear Camera and 2MP fixed focus front Camera, with 720P video capture at 30fps
  • Wi-Fi: 802.11 b/g/n (2.4G), sim type: Nano sim, dual and single SIM variants. 16GB Internal storage, expandable with Micro SD up to 128GB (not included)






About the author

Stan Durlacher

Stan has been involved with Design and Construction in the commercial industry since 1975. He is currently the President of Design and Construction for a major St Petersburg, FL developer. Before that, he was a Project Executive for a prominent Boston Construction Manager, building high-rise apartment and office buildings. One of the hallmarks of his career has been innovative problem-solving. As Assistant Secretary of Transportation for the Commonwealth of Massachusetts, Stan was instrumental in bringing the hydro mill slurry wall machinery and technology to Boston in the 1990s for use on the Central Artery Third Harbor Tunnel Project. Stan has been an avid woodworker since college and brings an innovative point of view to this field. Before Florida, he owned an 1886 farmhouse near Concord, Mass, and his skills and time were never idle for long. His barn and attached spaces serve as his ever-expanding workshop. Stan is a self-avowed tool hound. In 2013, Stan decided to design and build his own CNC router. This machine has become a centerpiece of his woodworking and craft focus. Stan will share many of the ways that this innovative technology has solved many current problems and how CNC will begin to impact the woodworking and home renovation businesses.

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