From Modu to CMF Phone 2 Pro: the brief history of modular smartphones

Modular phones are the talk of tech town again, thanks to the CMF Phone 2 Pro, the latest phone from Nothing’s sub-brand CMF. The phone comes with some impressive specs and brings a design which follows the Nothing industrial design ethos very well, but these are not the only reasons why it is making headlines.

Like the original CMF Phone 1, the CMF Phone 2 Pro brings modularity to the table and comes with special attachments that can add more functionality to the phone. The idea of being able to add attachments to your smartphone without risking ruining the device (we know people who like to play a little too much with how they handle their smartphones) is refreshing, but not new. Although CMF has brought the idea to a more mainstream market, modular smartphones have existed in the world and go back almost a decade and a half, if not more.

If that sounds hard to believe, check out these modular phones (from newest to oldest), some of which go back to 2000: 

CMF Phone 2 Pro & Phone 1

The CMF Phone 2 Pro (review), as well as its predecessor Phone 1 (review), came with good spec sheets and standout designs, but also brought modularity back to the smartphone world, although in slightly different ways. With the CMF Phone 1, you had to unscrew the back panel manually with a special screwdriver from the company and then swap it with a new panel and other attachments. That idea is modified a bit with the CMF Phone 2 Pro, where the back itself is not removable but you can screw on (yes, you will need that screwdriver again) what Nothing calls a Universal Cover, to which you can add attachments.

Both phones came with the option to attach a kickstand, wallet, and lanyard. With the CMF Phone 2 Pro, Nothing has added a new layer of modularity to this combination, allowing users to attach either a macro or a fisheye lens to the main camera capture pictures with completely different perspectives. Yes, unscrewing the panel is a bit of a hassle, but we so hope Nothing persists with modularity on its devices!

Xiaomi 15 Ultra

While the Xiaomi 15 Ultra (review) phone is loaded with high-end, flagship specs, it is the camera on the phone, made in partnership with the legendary Leica, that makes it stand out. The phone not only boasts three 50 megapixel sensors on the back (a one-inch main sensor, ultrawide and telephoto), but also features a whopping 200 megapixel sensor with up to 4.3x optical zoom. This has led many to call the phone a camera that also makes calls. And to drive the point home even further, Xiaomi has also launched a special camera kit, the Ultra Photography Kit (Legend Edition), which can turn the Xiaomi 15 Ultra into a proper camera and is perhaps the most versatile photography mod made for a smartphone.

The kit includes a multifunctional camera grip which can be attached to your phone via USB Type C port, a detachable thumb support, two detachable buttons (including a shutter button with half press to lock focus functionality), a zoom level, a video button, a customisable dial and a protective grip. As if that were not enough, the multifunctional camera grip comes with a 2,000mAh battery. Add to that a red decorative ring and a 67mm Filter adapter ring in the kit, and the kit morphs the Xiaomi 15 Ultra into a proper camera. We hope more mods will follow suit – perhaps a printer, or an attachable telephoto zoom?

HMD Fusion

HMD got on the modular phone bandwagon in 2024, releasing a modular smartphone called the HMD Fusion (review). The main focus of the device was repairability – users could repair broken parts of the phone themselves. The phone came with screws that one could open and replace parts like battery and display. The brand also promised that it will carry spare parts for the phone for at least seven years. That was not all.

The phone also came with a modular design. On its back were a line of pogo pins that connected different attachments to the phone. The HMD smartphone features two feature-based accessories –  a ‘Smart Outfit’ (as HMD named it), which has a ring light in it, to help you while creating content, and a full-fledged gaming controller called the Gaming Outfit, which, when connected, changes the phone into basically a gaming console.

HMD has promised a few more of these outfits, and the toolkit for making these Smart Outfits is open source, so the brand expects other developers to pick it up. The phone itself is very mid-segment, but the outfits make it special. Hopefully, the tech tailors will come out with more. 

Asus ROG Phone series

Asus’ ROG Phone line-up began with the Asus ROG Phone in 2018, and is now synonymous with high-end mobile gaming. The original ROG Phone was aimed at the gaming community and offered pure gaming pleasure with very high-end hardware, a trend that has continued to this day. The phone range has also come with modular attachments or, as ROG calls them, ‘Docksm,’ which were all gaming-centric too. The first ROG  phone came with a Gamevice controller and an Asus WiGig display dock that changed the phone into a console.

Moreover, there was a Mobile Desktop Dock which morphed the device into a proper desktop gaming device, and the phone came with a TwinView Dock, which added another 6-inch AMOLED screen to your phone’s gaming setup, packed front-facing quad speakers and two physical trigger buttons. There was also an AeroActive Cooler to keep heat levels low. This phone series remains basically every gamer’s dream device, and its mods clear the decks for gaming action. Pun intended.

Red Hydrogen One

The Hydrogen One, an Android device launched in the USA in 2018 by Red Digital Cinema, stood out for many reasons. In terms of innovation, the phone came with a 3D display (they were a thing once!) – a 4-view display that diffracted backlighting to depth, creating a ‘holographic’ effect. Similarly, the phone’s cameras could also be used to take ‘holographic’ 3D photos. And as if that were not enough, it came with expansion pins on the back, which could be used to attach an 8K camera developed especially for the smartphone by Lucid. This camera also supported 4-V and could use the Red Hydrogen One as a 3D viewfinder as well. Once again, it did not quite work out, but it remains an important chapter in modular phone history.

Essential Phone

We all best know Andy Rubin as the co-founder of Android, but he also designed a phone. Back in 2017, Rubin created a phone, which was quite ahead of its time. It came with a titanium and ceramic build, had an edge-to-edge display with Corning Gorilla Glass 5 protection and was the first mainstream phone ever to come with a notch. This was the Essential Phone. But apart from its then futuristic design, the phone also came with a 360-degree camera mod that could be attached to the top of the device and was launched along with the phone. It was not the only accessory, though. The Essential Phone did not have a 3.5 mm audio jack in its anatomy, just a USB Type C port, so it came with a mod that could be clipped on and added the 3.5 mm audio jack to the phone.

A DAC accessory and a charging dock accessory that could be simply clipped onto the phone were also announced. The Essential Phone won rave reviews for its innovation, but was not a success, and interestingly, the Essential brand was acquired in 2021 by a new startup co-founded by Carl Pei – Nothing. 

Moto Z series

Released in 2016, the Moto Z (review) series basically took the modularity game in smartphones to another level, with its Moto Mods. These were basically attachments that you could slap on the back of your Moto Z smartphone and alter its anatomy and add functionality in real time. These Moto Mods used to connect to the phones with the help of a line of pogo pins present on the back of the Moto Z series devices. The attachments were not ‘decorative’ and actually added a lot of value to the experience of using the device. Best of all, there were plenty of options.

Motorola made a camera mod in collaboration with Hasselblad that not only offered professional camera-level photography but also added 10x zoom ability. Then there was the JBL SoundBoost mod, which was basically a JBL speaker attached to the back of your phone. There was the Moto GamePad, which morphed your phone into a proper gaming console, while another mod, the battery powerpack, was basically a wireless charger attached to your phone, adding 3,490 mAh more to your phone. Other mods included a Polaroid instant share printer, a 360-degree camera mod, a projector mod and some style shells. We really think modular phones peaked here!

LG G5

Released in 2016, the LG G5 (review) was a notable device for many reasons. Its aluminium chassis and modular design were the key highlights of the phone. While the phone was not ‘regular’ in any way, it was its detachable ‘chin’ that was its most distinct feature. The chin of the phone could be detached by pressing a small button on the base of the left side of the phone. Doing this would detach the bottom portion, along with the battery of the phone. The new attachment then needed to be connected to the battery directly.

The phone offered two accessories, Cam Plus and Hi-Fi Plus – one was a camera grip and the other was a DAC accessory. The camera grip had a physical shutter button and a zoom-in and out wheel, and it brought along some of its own battery to add to the phone. The DAC attachment also had a 3.5 mm audio jack and a USB Type-C port. LG promised more mods but did not deliver, and the fact that the phone had to restart every time one swapped a mod was also a pain point for many. That said, it was a seriously cool device.

Modu series

This is the OG of modular phones. Made by an Israeli smartphone company and launched in 2009, the Modu phone allowed users to add several features to a core unit. It came with a number of modifications, which the company called “Modu Jackets”, that enabled users to alter the looks and features of the phone. These Modu Jackets were basically like a phone sleeve that allowed you to change the look of the phone or add physical functionalities like keyboard, music player and even a camera to the device.

For many people, the original Modu phone and its successor, the Modu T, remain the real benchmarks for modular smartphones, allowing users to choose which features they would like to add to their phones. That said, the phones were not commercially successful, and the brand was ultimately acquired by Google to develop its modular phone project, called Project Ara, which also never became a reality.