While 2.5mm was the original standard for phone headsets, the slightly larger 3.5mm size is standard for music headphones and is now the more common size on phones. See: Headphone Jack (3.5mm ...

Microsoftが2.5mm/3.5mmヘッドフォンジャックを薄型化する特許を2件取得している（US Patent 9,768,541、US Patent 9,793,641、MSPoweruser ...

It’s almost impossible to find a smartphone with a 3.5mm headphone jack these days, at least not in flagship phones. There’s also a big market for wireless headphones and earphones which are ...