In my mind modular phones is a false good idea. The principle is really good, but it is a lot more difficult to do that in a phone than in a desktop PC, due to the huge constraints on it (mainly size and weight)
And you are too soon reaching the limits of the technology you have to add the new modular components.

Take any phone you bought more than 6 monthes ago. Not a single one is capable to support the 41MPixel stream of the 2012's Nokia 808 . Simply because the rest of the hardware (system bus, memory speed, CPU/GPU processing power...) is not able to cope with it.

Modularity is something really hard to achieve to be able to improve your phone with technologies newer than the phone.

It can however allow to add some components of the same generation, but who will had a 720p camera to his 3 years old phone, when then new ones are doing 4k ?

Add to that that a modular phone needs a lot of connectors that take space and add weight, and to be modular you need to split some parts which don't allow as much optimisation as having a single board design, and you'll see that it will not be that much cost effective to create that modular phone.
It would be, if there were 10 phones of each kind sold, but it is produced by tens/hundreds of thousands units which makes it cheaper to produce 2 differents phones than a modular one + peripherals modules.

For a keyboard or the other TOH projects seen here it is okay, but not for core components like camera, connectivity (HDMI, USB, ...) and memory.

My 2 cents.

I suspect many mainframe engineers would have thought you were bonkers if you explained modular desktop PCs to them...

I reckon modularity is good (within reason), and phones will get there eventually. But not yet.

Vsenn is probably more likely, they are considering to support Sailfish OS, and also being Finnish makes it more likely:
http://http://www.digitaltrends.com/mobile/vsenn-modular-smartphone-news/
http://vsenn.com/

I hope it will be along with Jolla and TOH.

Ah, these wonderful concepts like the Other Half or Ara, providing modularity to small devices by such strange and exciting methods!

A long time ago in a universe far, far away, I recall mobile devices commonly used to have something called a "PCMCIA slot" (also known as a PC-Card slot). The PCMCIA card worked very much like an expansion card on a desktop computer, only miniaturized and designed for the power and space constraints of a laptop or other mobile device. And you could build space for such a card into a device's frame without making radical design decisions.

I'm not saying that the PCMCIA standard itself could be used in a modern phone; certainly, the cards are way, way too big. But I don't see why a small slot couldn't be carved out into the side of a modern phone with an OH- or Ara-like connector; something that might be deep enough to fit a small bit of electronics directly, and certainly allow a larger peripheral (or dock) to be connected when the user would like. (In my opinion, the existing OH and Ara concepts themselves demand way too much from a design; e.g., I have no clue how you'd be able to match the existing OH concept to the new Jolla tablet...)

But, Copernicus, don't forget that PCMCIA and its predecessors and successors were used only for adding peripherals. Storage, modems, NICs, card readers... Pretty mjuch what USB is used for nowadays. They were not used for core components like CPU or RAM.

This is not to say that you might not have a barebone module containing basically just the system bus of some sort and swappable modules with CPU+RAM (a single module), modem, WLAN, display, camera... Buth the mechanical constraints like size and durability will get in the way. A LEGO phone will have a hard time competing with a monolith.

I also suspect the innovation cycle, albeit looking promising in theory, will actually be slower than for the monoliths. By the time a new camera comes out as a swappable module, the competition will have made three iterations already.

Absolutely right! (Although I've never really been satisfied with current USB docking stations; I'd like to have a little more bandwidth for higher-speed storage, or even external displays. Though that may be asking too much.) But still, the advantage of the PCMCIA slot was that there was just a smidgeon of free space available, such that if you could build it small enough, you could squeeze your entire peripheral inside the case of the parent device. (In essence, both the OH and Ara are also trying to integrate modules into the devices frame, but they do it by breaking off entire pieces of the device rather than simply providing a small open region.)

But in any case, I agree, I just don't see the need for making the actual CPU itself modular. For me, the real advantage of having an expansion card is the ability to add unusual hardware, items that are not found on the standard device. (For example, very few phones today have CIR ports, something dear to my own heart...)

Yeah, that's what I'm afraid of. I'm pretty sure the Ara project is just going to fall flat on its face, despite the backing of Google.

Ultimately, it seems much easier to me to create a mini-Ara project, and just provide an Ara-like slot into other, more mainstream devices.

At least modern mainframes are actually quite modular, at least as far as fault tolerance goes - your usually hot-swap power supplies, storage and even CPUS (!) without interrupting normal operation of the given mainframe. Not sure if they can also cope with adding adding additional CPUs above what was present during the startup without rebooting the machine - some s390 jockey would need to confirm this.

About Tablet and TOH: theoretically, if tablet was designed like 2x phone (two cameras at the back, ability to connect two TOHs to the tablet's back), it would be very interesting. It would provide advantage of stereoscopic vision (if anybody cared to use it), large display (tablet, after all, has to be large), ability for two people to interact (be it for a chess game, or document-writing on an airplane), and other phabulous (play of words: fabulous and phablet) functionality.

About Vsenn...
It's not unusual to offer user-replace-able battery, though I do not see any advances in battery technology over time (Polarcell is a bit stronger because of size-volume, not quality-contents, imho).
It's possible to replace camera in Nokia N900 and such, but requires extreme care and caution, due to fragility - and, it's difficult to find something compatible and of higher quality-specifications.
RAM is easily replace-able in laptops-desktops - such a feature would be welcome in phones.
Processor replace-ability? Sounds like stuff of legends, with all the compatibility issues: you cannot put OMAP5 into hole from OMAP3.

Nice movement, but it will take a lot of work to make the phone future-proof through upgrade-ability.

I am not trying for Ara-like "design anything from any pieces"; rather, I am aiming for "choose whatever screen(s) and keyboard(s) you like", while core (processor, RAM, camera, sensors) remains the same. I just consider removal of screen as next logical step (see below), with two TOHs at the same time being a really nice feature.

If people can make a screen-TOH, what's the point of having a screen inside Jolla Phone? If people can make a keyboard-TOH, what's the point of having a keyboard inside Jolla Phone? [wait, Jolla Phone does not have a keyboard] If people can make a Toggles-Buttons-TOH, what's the point of having hardware buttons inside Jolla Phone? [wait, Jolla Phone doesn't have hardware buttons]

And yes, having the "vulnerable-malicious-power-hungry" components plug-gable in-and-out would help. Even if you would have to design custom-shaped USB pluggies, to make them fit the shape of the phone better: most people would just leave them inside, while the random paranoid people would be glad to have the option to take them out, or replace them with a different piece of hardware.

Best wishes. Thank you.

Another (Finnish!) modular option is Puzzlephone (http://www.tomshardware.com/news/puz...one,28138.html)
What I like about the idea is that it doesn't go to the unpractical extreme of Ara, but it defines just three modules: screen+speaker, battery + secondary electronics, CPU + primary electronics.
In March 2014 when they surfaced to public some tweets of reciprocal interest were exchanged with Jolla's @cybette.

Yeah, you're right.
But in the same time, if we take a look at desktop PC and laptops, that had 20/30 years to mature, you can see this trend:
They are not a lot modular ! At least not as much as some here want the phone to be.

If I take my desktop :
* network, GPU, sound.... are all integrated in the motherboard. So I can NOT change them. What I can do however is to ADD another one thanks to the fact the desktop case is 5 times bigger than was it inside.
* For the CPU, yes I could change it, but will never do: the socket LGA775 is not used anymore (superseeded by at least 3 or 4 newer ones), so I can not find a recent CPU to fit here that could provide me more value.
* RAM : yes I added some RAM, it is nice ! But I need it to follow the speed that is availlable to the CPU and motherboard : the speed we had 5 years ago, not what is in the market now...
* storage/peripherals: I have now 3 drives (HDD+SSD) + a DVD. Here it is also the fact that the case is 5 times bigger than needed that allows that. I also have several USB external things that are always plugged (keyboard+mouse to start, bluetooth sometimes)

If I now take the exemple of my laptop:
* I can change memory, but it was already sold with the max possible...
* I can replace the hard drive, but can't have 2 drives (SDD+HDD for example...)
* I can add external things through USB, but that makes it a lot less portable if it needs to be always here (think of a second hard drive, of can you carry that !)
* And that's all ! I can not even replace the battery to a bigger one as they don't exist (I can only replace it by the same if it fails). I can replace the motherboard as the case is built around and no other one will fit. The processor may be changed, but it is not made to be easy with the cooling system. I can't replace the webcam, the screen size, ...

So, how do you think we can easily have much modularity in a phone that have far higher size constraints, as it is not really good in mature products like laptops. Desktops are better in that regards, but there are still limits.

The puzzlephone may have the balance here right. We'll see how it ends up.