Natya Vidhan Biswas' Upcycled Beetel Phone Is Now a Slick Spotify Stream Selector

Developer Natya Vidhan Biswas has upcycled a long-dead landline telephone into something a little more musical and modern: a control device for music streaming.

"I wasn't planning to build anything that day. I was just cleaning my room," Biswas explains of the project's origin. "You know that phase where you start opening random boxes and suddenly you're three hours deep into 'why do I even own this?' That's when i found it. An old Beetel M59 landline telephone. Just sitting there. Probably hasn't been touched in like 5–6 years. Normal people would either ignore it or throw it away. I opened it."

For the younger readers, landline phones were how people communicated in the dark ages before everyone had an always-online supercomputer in their pocket with which to send each other memes. The earliest models connected you via overhead wires to an operator who would direct your call; the first direct-dialing models used pulses generated by a physical circular dial's sprung return movements, later replaced by a numerical keyboard generating touch-tones.

Biswas had another vision for the classic Beetel, though: figuring out how the keypad matrix was wired, in order to interface it to an Espressif ESP32 microcontroller and use it as an input device. "I was cleaning. Music was playing, and I kept needing to go back to my laptop to change songs," the developer explains. "And at some point my brain went: what if I could just… press something nearby? Then I looked at the phone again. And yeah. That was it."

Once traced out, the keypad matrix was connected to the microcontroller along with the hook switch: pick the handset up and the microcontroller begins monitoring the keypad, allowing the user to dial numbers associated with particular songs on the popular Spotify streaming service. There's an added bonus in the code, too: pick the handset up and the stream "ducks," quietening its volume while you concentrate on dialing; put the handset on-hook and the volume is restored.

The phone's liquid crystal display is repurposed to show information on the number dialed and the song currently streaming — though this is a replacement part, rather than the phone's own display. "The original display was cursed," Biswas explains. "No docs. Probably proprietary. No idea how to talk to it. So I didn't. I just replaced it with a 16×2 I2C LCD. Way easier."

The project is documented in full on Biswas' blog, with source code available on GitHub under the permissive MIT license.