Setting up JemRec

Everything happens on the phone. You will not need a computer, a cable, or a second app. It takes about three minutes, and you do it once.

Every step below was walked through on an Honor Magic 8 Pro running MagicOS 10, and the screen names are the ones that actually appear there. Other phones differ in wording; the shape of the process does not, and JemRec names the right path for your phone as you go.

Installing

Download the APK from the project's Releases page and open it. Android asks whether to allow installing from whatever you opened it with — a browser, or a file manager — and that permission is granted per app, not once for the phone.

Play Protect may object, and what it takes differs by phone. It warns about apps it has not seen before, which is every app that is not on Google Play, so this is not a judgement about JemRec. Three phones, three outcomes:

If yours refuses, those are the two things to try, in that order: open the file from a file manager rather than the browser, and only then consider turning Play Protect off for the minute it takes — and back on afterwards.

Every release is signed with the same key, so each one installs over the one before it. If you would rather check what you downloaded than trust it, apksigner verify --print-certs on the file should report SHA-256 50aeab3630f0198ea3845db51413b1ad29582f78240fa2df6fe55ba8537afdf8, the same digest the release workflow prints in its log on every run.

Step 1 — Open JemRec and allow notifications

1. Open JemRec.
2. It asks for notifications. Allow them.
3. It also offers to read audio files, which lets it list recordings made before a reinstall. Refusing that is fine; only the old ones are hidden.

Notifications are not decoration here. They are how the app tells you a call is being recorded, how it asks whether to record one, and where you will type the pairing code in step 4.

JemRec does not ask for microphone access and does not have it. The recording is done by a separate, more privileged helper that the app starts later; the app itself only collects the finished file.

Step 2 — Turn on Developer options

Skip this if Developer options are already on.

1. Open Settings.
2. Search for build number. It usually lives under About phone, but the path differs between phones, which is why searching beats hunting.
3. Tap Build number seven times.
4. Enter your PIN or pattern if asked.

You should see You are now a developer.

Step 3 — Turn on both debugging switches

Be on Wi-Fi before you start this. Wireless debugging only stays on while the phone has a Wi-Fi connection.

1. In JemRec, tap Open settings, then search Settings for Developer options. The app also names the menu it usually lives in on your phone — though on a custom ROM such as LineageOS it is under System, whoever made the handset.
2. Turn on USB debugging and Wireless debugging. Either order. No cable is needed and none should be plugged in.
3. If Android asks whether to allow wireless debugging on this network, tick Always allow and tap Allow.
4. Look at both switches once more. One of them can switch itself off the first time; turn it on again and it holds.

Why both. Wireless debugging is the channel JemRec uses to start its recorder. USB debugging — the setting, with no cable involved — is what keeps Android's debugging service alive, and without it Wireless debugging switches itself off again before the app can connect.

Step 4 — Pair, from your notifications

Read this step before starting it. The obvious approach does not work, and knowing why saves repeating it.

The pairing dialog exists only while Settings is on screen. Leave Settings — by switching to JemRec, or by pressing Back — and Android tears the dialog down instantly, taking the code with it.

The notification shade is different. It belongs to the system rather than to another app, so pulling it down leaves Settings running and the dialog intact. That is where you type the code, and JemRec posts the field before you go anywhere so it is already waiting.

1. In JemRec, tap Open settings.
2. Open Wireless debugging, then tap Pair device with pairing code. Six digits appear.
3. Swipe down from the top of the screen, over that dialog.
4. Find JemRec — pairing and tap Enter code.
5. Type the six digits and send them.

You do not need the port number. JemRec finds that itself.

Then watch that same notification. It says what is happening, and if a debugging switch turned itself off it says which one — turn it back on and the app connects by itself. There is no need to pair again or to fetch a new code.

Step 5 — Wait a few seconds

JemRec does the rest by itself: it grants itself the one privileged setting it needs, starts the recorder, and begins watching for calls. When it is done the header says Ready to record.

There is no permanent notification. The app is dormant between calls — the recorder is a separate process that does the watching — so a notification appears only for the length of a call.

Step 6 — Test it

Call someone and talk for twenty seconds, with both of you speaking.

• During the call a notification says Recording call.
• After you hang up, open JemRec. The recording is at the top of the list.

Files are named like 20260907_150909_out.ogg — date, time, and in or out for the direction. They are ordinary Ogg Opus files that any player can open.

If your recording has only your own voice on it, that is the one thing no app can fix: your phone's audio hardware does not hand the other side to apps at all. Settings → Diagnostics → Self-test answers that in about a second, without ringing anybody.

Where recordings go

The phone's standard Recordings/JemRec folder, which any file manager or music app can open, and which survives uninstalling the app. To use a different folder, open Settings and tap Change under Saving to.

Choosing when to record

Record every call, in Settings, decides this.

• On, the default: every call is recorded and you are not asked.
• Off: when a call starts a notification appears with Record and Not now. Nothing is captured until you tap Record, so the opening seconds of that call are not saved. That is the honest cost of being asked, and it is why the switch is on by default.

The prompt stays up for about a minute rather than the few seconds an ordinary notification gets, and if you miss it, it waits in the shade for the rest of the call. On a locked screen you get the same question full screen.

Playing, sharing and deleting

Tap a recording to play it inside the app; a scrubber appears under the row, and the chevron beside it folds the player away. The share button offers the original file or a converted copy that plays anywhere.

To delete, tap a contact's photo or long-press a row to start selecting, tick what you want, and use the bin in the toolbar. It asks first and tells you how many. Deleting is permanent.

Recordings are kept when JemRec is uninstalled, because they are yours rather than the app's — so if you want them gone, delete them before you uninstall.

Turning JemRec off

The switch in the header is the on/off control for the whole app. Off means no call is recorded and no notification appears. Your recordings and your pairing are untouched, and the recorder itself keeps running in the background doing nothing — which is what makes turning it back on instant, anywhere, with no network.

After a restart

A reboot kills the recorder, and building it again takes a few seconds of Wi-Fi. Until that has happened, calls are not recorded and the header says so. Whether it happens without you comes down to one setting on your phone.

Allow JemRec to start automatically

This is the fix, and it is worth doing once. JemRec's own Settings has a Survive a restart card with a button that opens the right screen on your phone, because the list is four levels deep and called something different on every make. On an Honor it is Settings → Battery → App launch; find JemRec, switch it to Manage manually and leave Auto-launch on. Xiaomi calls it Autostart, OPPO and vivo have their own. The card only appears on a phone that has such a list.

What it buys, measured on that Honor: the app was started by the boot broadcast at 21 seconds of uptime, armed its scheduled job and asked the system to wake it when Wi-Fi appeared, and the recorder was back ten seconds after Wi-Fi came on — with the app never opened.

Without it, open JemRec once

The same phone with auto-launch off does nothing at all. The system declined to start the app for the boot broadcast — don't meet cpuload, in its own log — so neither the job nor the Wi-Fi watcher was ever armed, and seven minutes after Wi-Fi returned nothing had come back. Opening the app had it recording sixteen seconds later.

So if you would rather not touch battery settings, treat opening JemRec once as part of restarting the phone. It always works.

Either way: Wi-Fi is needed to rebuild the recorder, never to use it. Once it is up, calls are recorded with Wi-Fi off, on mobile data, anywhere.

What the app tells you

The header is the honest indicator:

Settings

• Record every call — record everything, or be asked each time.
• Saving to — which folder recordings go in, with a Change button.
• Show who called — labels each recording with the contact's name and photo, or the number when they are not in your contacts. Optional, and asked for in the app rather than at install, because it needs your call log and contacts. Say no and everything still works, with the time as each recording's headline.
• Start fresh — puts JemRec back to how it was the day you installed it, so setup runs again from step 1. The app closes when you confirm. Your recordings are not deleted.
• Diagnostics — whether the recorder is running, a self-test that proves a call would be recorded, and a way to start the recorder by hand. It is what a bug report wants.

If something goes wrong

Pairing fails every time. Almost always the dialog closed. It survives only while Settings is on screen, which is why step 4 uses the notification shade rather than switching back to the app. Reopen the dialog for a fresh code each attempt.

A debugging switch keeps turning itself off. Some phones do that the first time one is enabled without a cable, and Android turns Wireless debugging off whenever Wi-Fi drops. Turn it on again with Wi-Fi connected; it holds the second time.

It says it cannot record. Join any Wi-Fi and leave it a few seconds; the app rebuilds its recorder without being asked. If you would rather not wait, Settings → Diagnostics → Start recorder.

Recordings have only your voice. Your phone's audio hardware does not expose the other side to apps. Nothing in any app can change that, and the self-test will tell you plainly.

Uninstalling

Uninstall it however you like — long-press the icon, or Settings → Apps. There is nothing special to do.

The recorder is a separate system process rather than part of the app, so removing the package does not stop it immediately. It checks every few minutes whether JemRec is still installed, and when it is not it turns both debugging switches off, deletes its own files and exits. A reinstall is never fooled by one that has not got there yet, either: the app only trusts a recorder it started itself, and retires any other on sight.

Two honest warnings

The other person is being recorded too. Whether you may do that without telling them differs by country and sometimes by region. That is your call to make, not the app's.

This uses debugging switches, and they stay on. They are developer features that let software on your phone act with elevated privileges. JemRec needs them to record calls at all. If you stop using JemRec, turn Wireless debugging, USB debugging and Developer options back off.