This application enables the user to transmit data between air-gapped devices using audio.
It uses a simple MODEM algorithm to enable the user to send and receive short data messages (up to 250 bytes within up to 3 seconds) between nearby phones or computers utilizing the sender's speaker and the receiver's microphone.

Please use GitHub (https://github.com/romanz/audiomodem-android/issues) to report any issue you have with the application.

You can also use the following Python implementation (https://github.com/romanz/amodem) to communicate with a computer.