Virtually all smartphone manufacturers have eliminated the 3.5mm audio jack even though it has long been the standard connector for a huge range of audio equipment over the past century.

The 3.5mm headphone jack is an industry standard audio plug. Most commonly used for connecting a pair of stereo headphones to your smartphone or 'piping' your audio from your phone to an external ...

Those include the PCB and wiring, but not the microphone element itself. A 3.5mm audio jack is added to the flash case, and soldered to the microphone cable. Now he has a modular audio-in jack.