[BugWatch]

Hm, IIRC if you still have an (ideally forward-facing) headphone jack, I believe there were cheap plug-ins (essentially IR LED on a 3.5 mm connector) that would provide the functionality given a proper software.

[jeroenhd]

True, but audio jacks are hard to find in anything above a midrange phone these days.

You're also often limited to the app provided by the manufacturer of the 3.5mm dongle, which isn't always great.