iPhone doesn’t support recording phone calls, so the only way to record audio during the phone conversations is to basically add a third party to the call who can record whatever is being said.
Now, there is a number of available options including Google Voice and what not, but I wanted to build an independent and more privacy-centred one, and have fun with the project.
Effectively, all you need is a Raspberry Pi, a 3G/GSM dongle and a second SIM card (check Pay As You Go plans in your country).
I have not created the underlying technologies myself, but rather merely created an automated setup and configurator for easier use.
A lot of people expressed their concern about legal implications when I first posted this project on Reddit.
Indeed, many countries oblige you to notify the other party about the fact you're recording the call.
I am not a lawyer, so do your own research of your local legislation, obey it and get a legal advice if required.
If in doubt, avoid recording phone calls.
TL;DR: I built this tool for fun as a proof of concept and did not intend for it to work perfectly.
This code does nothing but installs and configures third-party software (Asterisk PBX and chan_dongle).
As a matter of fact, that software may get compromised (or have been), may be faulty, buggy or might even render your hardware unusable.
On top of that, I have not done much bash scripting in my life.
I built this as a fun DIY project, and think of it as simply a proof of concept at this stage. The hardware I used is a Raspberry Pi, an old 3G dongle I got for free a decade ago and a free SIM card, so I couldn't care less about any issues.
On top of that, 3G modems often need a lot more current than a Pi can give. Can this damage either the Pi or the dongle? Absolutely.
Feel free to make suggestions or contribute to the project.
- A Linux computer.
- I used a cheap Raspberry Pi 2, and tested it on Raspian Buster Lite (kernel 4.19)
- 3G USB modem. Important: not all of them support voice transmition. The older ones (circa 2010) should, the newer ones reportedly only support data transmition. Do your research.
- Any SIM card that fits that 3G dongle. Any "Pay As You Go" SIM should cut it.
Clone this repository to your Raspberry Pi.
Edit the values of DONGLE_IMEI and WHITELISTED_PHONE_NUMBER in the "Configuration" section in install.sh, then execute it as a user (without sudo):
./install.sh
You can open the Asterisk terminal with:
sudo asterisk -rvvvvv
The vvvvv bit makes the output more verbose, so you should be able to see when your call is received, picked up and routed to a correct context and extension.
Your call recordings will be available at:
/var/spool/asterisk/monitor/
You can copy the recordings from the computer by running an scp command, using a shared folder or putting some automation in place.
When you play a recording, you may notice a very sharp sound at the very beginning. I haven't looked into removing it yet and most likely won't, although feel free to submit a pull request with a fix.
You will need to make a 3-way conference call.
Different phones do it differently. Below is the description for iOS:
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Open your contacts or phone app and make a call to your recording line.
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When asterisk picks up, tap "Add Call". This will bring up the contact list.
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Select a contact or enter a phone number. During that call the asterisk line will be put on hold.
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Once connected with the other party, click "Merge" to create a three-way conference call.
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Once successfully merged you should be able to hear the other party, and asterisk will record both parties.
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Make sure to let the other party know you're recording the call.
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When you hang up, asterisk will stop the recording and save it in a folder of your preference.
Q: Can other people abuse my line?
A: If you properly set up the white list, only your calls will be picked up.
Q: Can I have multiple whitelisted numbers?
A: Yes, you may add something like exten => _+X.,1,GotoIf($[${CALLERID(num)} = 00000000000 | ${CALLERID(num)} = 00000000000]?allow:reject) to whitelist two numbers (in /etc/asterisk/externsions.conf). Following the same principle, you can add even more numbers. You will need to restart asterisk by running sudo asterisk -x "core restart gracefully"
Q: Can I use a different directory to store my recordings?
A: Yes. Find the line same => n, MixMonitor(${CALLERID(num)}-${STRFTIME(${EPOCH},,%d-%m-%Y-%H-%M-%S)}-${UNIQUEID}.wav) in /etc/asterisk/extensions.conf. The argument in MixMonitor is a file name. If you prefix that with an absolute path to the folder you want to store your recordings in, just add that before the file name. For example: /var/recordings/${CALLERID(num)}-${STRFTIME(${EPOCH},,%d-%m-%Y-%H-%M-%S)}-${UNIQUEID}.wav. Make sure asterisk has rights to write into that folder.
- Asterisk community with its amazing project
- bg111 for creating chan_dongle and Walter Doekes for maintaining its up-to-date fork
This code is licensed under the MIT license. Be aware that other pieces of software that this tool manages may be subject to additional license agreements.