Why Three Words

In case you did not know, What Three Words is a system that assigns three words to a location in the world within a few metres.

What is the problem this is trying to solve?

Well, the issue is that people often have an exact location but need to convey that to someone else. The classic example is someone on a telephone call to Emergency services. Reading, Speaking, and Typing a latitude and longitude is very error prone. Reading, speaking an typing three common words is less so.

Does it work?

To be frank, I don't know. But the words can easily be confused with similar words. There are examples where one letter, making a word plural, can give a location a few miles away (though often misheard words will be a long way apart).

Is there a better solution?

Yes, emergency services should get out of the stone age and stop being based on phone calls. A common API to allow calls for voice and video to emergency services with supplementary data should be developed by international co-operation, and become standard on mobile phones. It could allow not only voice, and video, but location data and medical data (many phones have medical data and can even do an ECG, report pulse, temperature, blood sugar, all sorts). This would solve a lot of problems, and I am sure mobile phone operators would be on board with this.

Other ideas?

Well, the issue here is communications. Someone has a device that knows the location and is on a call to someone that needs to know it - whether emergency services, vehicle breakdown, or heck - pizza delivery! How to get that location from an app on the device to someone on the end of a call. That is what W3W does.

Here's an idea...

DTMF is standard on audio calls, and even over mobile it has out of band encoding to work reliably to/from the mobile device if needed. So how about phones (or an app you install) work out that the other party has sent a DTMF sequence. DTMF in to a mobile is rare so something simple like "20" in DTMF would be more than adequate. The phone / app pops up saying "send location?" and if you say yes it sends that as DTMF. A simple *latitude*longitude# would suffice. Maybe use some less common A-D DTMF codes to frame it instead. Of course this could be something an app can send anyway without an in call prompt if the user commands it. It needs some common standard for the DTMF sequence to use, and maybe a check digit is in order.

This would be very easy for the phone app to do. Someone just needs to write a spec. But importantly this is very easy for a call centre system like emergency service, vehicle breakdown, or anyone, to handle automatically. No special API. DTMF is really very standard.

It may be a neat way to do this for now until we have proper multi-media APIs for this.

Or, you know, another "standard"

Plus codes look pretty neat and not that hard to speak. More on the spec here. Given the common usage of using 4 characters and a location name rather than all 8 characters before the plus, this can give a pretty good location with only 4 letters rather than 3 words. Emergency services have a rough location from cell ID anyway, so this has to be better than W3W. Notable some phones (android) have this coding available without installing an app even!

Or even easier than DTMF...


  1. All UK emergency services already have access to location for any vaguely modern mobile phone - see https://blog.google/around-the-globe/google-europe/helping-emergency-services-find-you/ for more on the Android implementation but iOS has something similar.

  2. Last time I called UK Emergency Services was when I was using a 2G phone. They could immediately see my rough location from the cell information and just asked me for a landmark or a road name to confirm it and place me within the cell.

    I was in a London suburb.

  3. One of the many critiques of W3W: https://shkspr.mobi/blog/2019/03/why-bother-with-what-three-words/

    An alternative called "What Three Fucks" based on triangles and swearwords seems to have disappeared from the internet, but can still be found on the Wayback Machine: https://web.archive.org/web/20191205132154/http://www.what3fucks.com/

  4. Specifically for 112/999 calls on 3GPP networks (GSM, UMTS, LTE, 5G NR), there's already a built-in location service (ETSI TR 103 393) which uses WiFi and GNSS locations to allow your handset to simultaneously send an SMS to the emergency services giving your location.

    Android 6 and above with Google Play Services and iOS 11 and later definitely support AML in the UK on emergency calls - so you call 999 from your mobile, and the other end gets your location as an SMS.

    There's plans for IMS-based networks (4G, 5G and WiFi Calling calls, but not 3G and 2G calls) to send the AML data as a SIP header; in theory, at least, the networks could then pass that SIP header to approved non-emergency numbers (101, 0333 2000 999, 0800 88 77 66 etc).

  5. Please stop suggesting SMS with links in. They are worse than useless to people with dumb mobile phones, they are actively confusing since they are just a long sequence of letters which are nigh on unreadable. My mum and dad get very flustered when sent links to their 2G phones, they think the phones are broken or someone is trying to hack them.

    Smartphone penetration is not universal. There is still a reasonable proportion of dumb mobile phones, it was 20% in the UK only a couple of years ago. And my landline will receive SMS, properly not text to speech, but obviously it can't handle links.

    1. Oh I agree, but the use case for w3w is someone with a phone smart enough to not only have location but have a w3w app to tell you the three words. Given that you have such a device, an sms is going to always be better than w3w.

    2. Not on an iPad, which I have (with 4G data). Apple don't allow SMS to/from iPads, but they can do w3w.

  6. I've seen this work really well in countries like India where addresses are much more haphazard - usually something along the lines of 'Building B, Plot 56, Near Phoenix Mall, Corner of Viman nagar, etc'

    Smart phones are pretty much everywhere and English is a second language for many so w3w is accessible. Even if they don't have a smart phone, they only need to find out their home w3w once from a friend and can quote it any time they need a delivery.

    I agree the emergency use case is less appealing, relying too much on having any form of 3/4/5G coverage in the UK which is still hit and miss, even in 2021

    1. Indeed, but for something like delivery address I see plus codes as much more useful to be honest, and probably less likely to be mis heard or mis quoted.

  7. Among the problems I have with What Three Words, it is available in many languages - which have different dictionaries.
    So if Jean-Pierre comes to the UK on holiday, his What Three Words location won't match the UK words.

    1. Which rather defeats the point of it being global. You have to have English w3w to make sense to someone with English w3w. Why not have UK w3w and French w3w, and so on, making for much shorter word lists to cover a country! (That is if it was vaguely sensible in the first place).


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