The Arduino is programmed to mimic a keyboard, so the datalogging is achieved by allowing the Arduino to ‘type’ the data into an open Excel spreadsheet.

They used the webaudio API to send serial data to a remote Arduino. The hack uses a FET, a capacitor, and a few resistors. They didn’t quite build a real modem with the audio.

Particle’s Electron is a “cellular Arduino” with a global data plan ARM- and GSM-based board promises quick on-ramp for mobile IoT development.