Reuse an old smartphone

The focus of this notes are older unused Android devices sitting in my drawer.

It might make sense to have administrative privileges on the device, either by rooting it or by installing a custom OS.

There are advantages and disadvantages, but if the device is otherwise sitting in a drawer, it might make sense to experiment with it.

The main issue is that such devices might not be supported anymore.

Not being supported by the manufacturer means that there will not be security updates, possibly making it an issue to connect the device to the internet.

Not being supported by the community means that tools for unlocking the smartphone might not be available anymore.

LineageOS, for example, does not keep older ROMs for devices it does not support anymore.

One can download the builds from external websites, like https://lineage-archive.timschumi.net/, https://archive.org, or https://lineageosroms.com/, but it needs to hope (as the official website does not even provide checksums) that the artifacts have not been tampered with.

The official alternative recommended by LineageOs is to compile the OS yourself. Instructions are provided, but the system requirements are not always practical: 300GB of space or more for building one ROM for lineage-18.1, recommended 32GB of RAM. It is not impossible, but it is an overkill for a casual user.

Having said that, it is not necessary to install a custom ROM.

Older devices might be easier to root (as they might have old and unpatched programs), but even administrator permissions are not required to find something useful to do with an otherwise unused phone.

My devices are not able to execute the Play Store; either the version of Android is too old (on Android 2.2 it was still named "Android Market"), or are not powerful enough to execute all background services required by it.

And even if the device is new, or powerful enough to execute the Google Play Store

F-Droid is a useful "alternative" store. It does not require an account or background services. You will not find programs of most companies (Twitter, Netflix, …​), but it gives you access to a wide catalog of open-source applications (Firefox, VLC, Termux, games, synchronization programs, …​).

This is probably the best idea.

If my main phone dies, I would really want to be able to extract the SIM card and use my old phone as if I’m still using the current one, until I get it repaired.

This means moving the SIM card and still having access to my email, chat applications, game scores, and web pages in the browser…​

Unfortunately, I know no way to accomplish something like that.

Some applications (my bank application, some chat applications like WhatsApp, …​) do not want to be installed and activated at the same time on multiple devices. Also, before configuring those applications on the new device, you might still need to access the old device.

Also, there is no "universal" way to back up your data, and unless you root your phone, you are severely limited if you do not want to take into account "the cloud".

Still, even with administrator privileges, you will not be able to backup and restore some applications, unless both of your devices are the same model.

This means that on one phone in the drawer I’ve configured my mail client, synchronized my contacts, and installed other applications that I find useful (sometimes older versions as it has an older version of Android), but I am still missing a lot of content for defining it as a short-medium term replacement device.

In my case, the SIM slots are also different, thus I’m not even able to remove the SIM from my current phone and place it in the older one, at least without an adapter.

That’s an easy one, Android phone can do a lot of things, playing videos and music too.

Granted, a smartphone might be too small for watching videos, but an unused tablet can do the job.

Especially for long rides, using a second device means avoiding consuming the battery of the primary device.

It can also be useful if one wants to share a device, for example with children and teenagers.

Otherwise, you could leave the device attached to a speaker in a room, for example, the kitchen or studio.

While most Android devices will already have a media player, I prefer to streamline my experience and use the same application where possible.

VLC it the media player (installable through F-Droid) one should always have at disposal.

While it can be used as a music player too, I find using a separate program, like Phonograph Plus or Vinyl Music Player as media Player more practical.

On one device I had some issues accessing some content, in that case, I’ve resorted to Vanilla Music.

You could place the phone on your working desk or your bedside table, and with DAVx synchronize your calendar.

It is possible to configure the phone to notify you with a ringtone before certain events, thus using it as an agenda to look at, synchronized with your other devices.

You could even try to set up something like a magic mirror.

There are a lot of Games for Android, many of those are free, some even open source, some examples

And then you also have at your disposal, catalogs for other consoles thanks to emulation.

Devices like the Game Boy or NES can be emulated more or less on all Android Phones, other consoles might require more powerful devices. RetroArch offers a unified interface for multiple game emulators.

The main disadvantage of emulated consoles is that they are more enjoyable with a physical controller.

On the touch screen, you do not feel where the controllers are located, making it easy to press the wrong button, or not press anything at all.

One possible solution is to attach an external controller, or use some bump dots and metal (aluminum foil tape, …​) to create your own "buttons".

If the bump dots are transparent, it should not be an issue if the controls are positioned over the game.

By doing so, you can find your controls more easily.

The only drawback is if you plan to play some "native games", as at that point using the touchscreen gets impractical.

One of the main use cases I have for an old Laptop was as webserver, the same holds for a phone too.

With Termux, it is possible to install a web server, The Apache HTTP Server Project, nginx, caddy, and lighttpd have already been packaged and can be installed with pkg.

I did not test how well it works, and one also needs to consider that the Android System does not like applications in the background, and it might kill the server process any time for a better user experience 🤦.

Similarly, one can setup SSH, and access the phone remotely, using it as backend for backups, for long-running jobs that do not require much power; for example, verifying periodically that a website is up, and send an email in case of errors (there seem already to be an app to cover such use-case: Keep it up).

There are many other, more or less valid, use cases depending on the sensors and equipment of your device.

If it has an accelerometer (most if not all devices) and/or a gyroscope you can use it as a bubble level.

If it has a camera (most phones), then it can be used for taking pictures, recording videos, reading QR codes and bar codes, and as a flashlight. Can also be used as a "security" camera, and notify you if something unexpected happens.

If it has a clock (is there any Android phone without a clock?) then it can be used as a clock (duh), alarm, timer, pomodoro timer, …​ The default clock application should be good enough for those tasks, if not, there are thousands available for free.

If it has a compass (which is not required for GPS), then it can be used as a compass (duh).

If it has GPS (most phones should have it), then it can be used for online and offline navigation and tracking.

If the hardware and software support it, you can use your phone as a Wi-Fi repeater. On my phone, I was able to share my Wi-Fi connection successfully with VPN Hotspot, but it requires administrator privileges to work as a repeater. Otherwise, LineageOs seems to support this feature out-of-the-box; just enable Wi-Fi Hotspot tethering while connected to another network via Wi-Fi.

Some phone models might support this feature out-of-the-box, no need to install a separate application and get root permission.

Some useful applications for taking advantage of specific sensors are

Does it make sense to use a separate device?

If you are now carrying two devices with you instead of one, it would not seem so.

For example, why use an old phone as an automated reminder or music player instead of the phone you are already using daily?

I can see some advantages in a second device in a fixed location, for example at the desk. The main advantage would be having an independent (and thus hopefully more reliable) system.

It wouldn’t be the first time, that I have not noticed a reminder on my phone, either because I lowered the volume (maybe because I was in a meeting, had to put it on silent, and forgot to set it on loud again), left the phone somewhere else, or because I had multiple, different reminders on the phone, and overlooked the relevant one.

Having one dedicated device can make its usage less error-prone.

If it is a music player, just turn it off, nothing else will be affected. If it is the reminder on the desk, I might not turn it off, but the worst can happen is that there is a small chance I get a notification for a reminder at an inappropriate moment, while with the phone I use usually, chances are much higher, as it could be a notification for an email, a phone call, a chat message, …​

Yes, it might be that I am terrible at managing my phone and that it is possible to group notifications in categories and turn only some of them off. Until the next update changes how the whole system works again.

Another advantage is that sharing such a device is easier. I might not want to give my phone to someone else just to watch a video or play some games, but I see no issues doing so with an old spare device dedicated to that task.

Another point is that some form of usage might require to "adapt" the hardware; like adding the bump dots for retro gaming. This makes using the touch screen for other tasks much more annoying. At this point, you are better served with an external controller, that will surely have its battery and needs to be connected somehow to the phone, which for my sporadic use does not make much sense.

Having listed the advantages…​ I would not buy a second phone for any of the listed uses, as using only one device has the advantage of having…​ less devices to maintain and configure.

On top of that, I prefer dumb devices, even better if they do not require a battery to function correctly!

I would probably buy a second one if there were a foolproof method for using it as a reliable fallback device, with some applications (chosen by me, the end user, not the author of the applications or phone manufacturer) synchronized offline.

The listed use cases (for me) make mainly sense as the alternative is having a device taking dust in the drawer. And even in that case, after some time such phones might return in the drawer.