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Monday, March 07, 2011

Time for the word "terminal" to reach the end of the line

I stirred up a bit of debate over the weekend via posts on Twitter suggesting that the use of the word "terminal" in the telecoms industry is always a good sign that the speaker is stuck in a legacy age. (Twitter being the terrible medium for debate that it is, I was unable to discuss this meaningfully - hence this post).

Typically used by network-centric, standards-centric, telephony-centric members of the industry, I have long believed that 'terminal' exemplifies the denial of reality endemic in many "old school" telecoms professionals. Nobody outside of the network fraternity uses the word "terminal". You'll never hear Steve Jobs, or even most of Nokia's current and former execs utter the term. People say "mobile", "device", "cellphone", "smartphone".

This is not a new stance of mine either - I made the same point almost exactly 5 years ago in this blog post.

After a bit of a verbal ping-pong match with @TMGB this morning (I'm tempted to describe him as the dinosaurs' "Chief Asteroid Denier", but that's perhaps a bit unfair), I've reached a slightly clearer position. In historic telephony standards, there is indeed still a specific technical notion of a "terminal" defined. It's a bit similar to the old mainframe/green-screen architecture, or various other technology domains like industrial SCADA systems.

But in the past, being a terminal was pretty much the only thing that a phone did. Even more recently, being a terminal was the main or most important thing it did, even if it was as an SMS terminal rather than a telephone terminal. Therefore it was fairly natural for people to refer to any mobile phone as a "terminal", firstly because that was the only type of device, and secondly because it was - to all intents and purposes - the only useful thing it did.

But obviously, over the last 10 years, things have changed. Modern devices do a huge range of things - often simultaneously. Acting as network terminal in a standards-based, telephony sense is simply one of a smartphone's functions, and increasingly not the most important. Many of those functions are not even anything to do with a network connection - the camera, MP3 player and so on. Arguably, connectionless technologies like HTTP and IP do not have "terminals" in the telecoms sense of the word. The majority of device value thus resides in "non-terminal" functions.

Using the word "terminal" now to refer to a smartphone or other new device is therefore extremely sloppy. Today, terminal=function in mobile, not terminal=physical product. And yes, this is more than just an abstruse semantic discussion, because perpetuating the idea that the terminal function is somehow the paramount use case of a device- and, moreover, is independent of the other functions is a huge fallacy which may drive the industry down blind alleys.

The idea that a telephony call (the most obvious example of the terminal function) should over-ride anything else the device or user may be doing is not just arrogant, but a huge error in understanding user behaviour and modern OS's. Yet that remains an unspoken assumption among many in the industry.

Often a smartphone (or, certainly, tablet) user will be doing many things more important than receiving a phone call, particularly a trivial one from somebody they don't want to talk to. Yet the "terminal is the #1 application" mentality is insidious - standards like Circuit-Switched Fallback for LTE telephony assume it to be true. Multi-tasking, multi-connection devices mean that the terminal capability does not exist in isolation - and concurrent tasks need to be considered and sometimes given priority. This will need clever UI design, as well as various user interactions in the device's upper software layers that are not generally considered in network-centric views of "terminal" behaviour.

Furthermore, as we move towards smarter devices and especially VoIP-based telephony, the idea that the "terminating software client" is actually the last point of the chain becomes ever less true. The OS, or another application or browser, might intercept a phone call before it reaches you, or initiate an outbound one on your behalf. The ultimate "voice" application may simply be calling a telephony API - or may pick-and-choose other non-service based voice capabilities.

In other words, even the word "terminal" becomes factually incorrect.

So, to be clearer:

The word "terminal" is a legacy of a time when mobile devices were primarily intended for connection to specific services (especially voice telephony), over a network access run by the same service provider. Nowadays, a mobile device may have a terminal function but can also operate in many other modes - standalone & offline, connected to another network (eg WiFi), using a specific installed app. It is therefore not just factually wrong, but dangerously naive to continue referring to it as just a "terminal" - and thus I believe I am justified in my views that continued misuse of the term is a good indicator of the mindset of the person saying it.


Dan (aka @tmgb) said...

As 'Chief Asteroid Denier' I feel I ought to clarify the Twitter comments.

I agree that the term 'terminal' to describe any device is a misnomer, but equally, I don't believe it was ever being used correctly. The Terminal Equipment function in a device is a specific function, defined in specs and with a clear demarkation and separate role from the rest of what makes up a device (or User Equipment). A dongle has a terminal equipment element; so does a laptop with an embedded mobile chipset, a smartphone and a Nokia 6110.

All the devices above though are more than just terminal equipment. They have additional functionality and applications that take the output from the terminal equipment and turn it into something that other elements of the User Equipment can understand and process, and then where relevant, present to us in a way that is relevant to the application it relates to. These are the functions that go around the 'terminal' and turn it into 'User Equipment'.

Drawng this distinction is a purist point, and perhaps some of you may view it as being a further Asteroid dodge, but then I am a purist. My point is that a wholesale banishment of the term 'terminal' would result in the blurring of the lines of the fucntional elements that make up a device. The functional element that terminates the Radio Access is an important part of what makes a device . Whether the traffic that is being transported is a voice call, a video clip, information specific to an application or an OTA update is for the other elements in the device to sort out, but none of that is visible to the device until the lower layers have been terminated.

I don't argue against the fact that using 'terminal' to describe the whole device is wrong - but that is mainly because it always was wrong. I do argue however, that there is a need to correctly identify the 'terminal equipment' function, and for that, there is no better term. Unfortunately as is often the case, once the industry gets hold of a term and determines that it means something different to what it was meant to (4G anyone?), unwinding the problem becomes nigh on impossible.

If anyone is very bored, take a look at 3GPP 24.002 and 27.001, .002 and .003 where all of this is explicitly defined. It is in that context that I will use the term 'terminal equipment', and perhaps not deny that asteroids exist, but point out the ones that have always been there. If I'd made the points above 10 years ago and said 'terminal' should be 'user equipment', no one would have cared. I suspect that not many people will care now either.

Jason Devitt said...

"Often a smartphone (or, certainly, tablet) user will be doing many things more important than receiving a phone call, particularly a trivial one from somebody they don't want to talk to. Yet the "terminal is the #1 application" mentality is insidious."

This is so true. My company Mr. Number makes apps for screening your calls and texts - we block calls from people that you don't want to hear from again and (in the US) offer caller ID for numbers that you don't recognize.

The number one complaint that we get from our users is that we don't get to the call fast enough. They don't want to hear the phone ring. They don't want to know the call even happened - they asked us to delete blocked calls from their call log, so now we do. What our users don't realize, and what we're constantly fighting against as developers, is that their phone was designed with the assumption that answering a call should take precedence over everything else. When the only other "apps" on the phone were "clock" and "address book" that may have been true. It isn't now.


Dean Bubley said...

Thanks Dan.

Agreed then, "terminal equipment" is a function, "user equipment" is the physical device.

Gets more complicated when using WiFi though I guess, as the radio can simultaneously be acting as opeartor-oriented "terminal equipment" and a private IP connection


Anonymous said...

I disagree with the above. Using terminal to mean "voice terminal" marks you as an old telecom person; using terminal to mean an end user device is fine.

Terminal in current usage just means end-point. User-terminal, mobile terminal, etc are all quite accurate and useful as they mean just as they say...this is one end point for whatever the app or apps user is working with.

The word terminal comes not from telecoms but from IT; wherein a terminal was (and is still, albeit rarely) a relatively 'dumb' window into a world of processes running on any number of machines in the cloud...sometimes, but not always, within a single mainframe. Dumb terminal vs. smart terminal is a never-ending battle between edge processing power and bandwidth of course...smartphone apps were winning last year but maybe cloud is making a comeback with fixed fiber and mobile LTE (google certainly hopes so).

Until I read this article I hadn't even considered that terminal meant a voice device specifically :)

Of course I've only been in telco for a bit over ten years, and all on the internet/data/smartphone side of the house.