> At the time, the vast majority of phones came with a non-standard 2.5mm jack for a wired headset.
The 2.5mm jack used on pre-iPhone wireless phones wasn't non-standard, it was a pre-existing, widely adopted standard for hands-free phone headsets established initially for cordless phones (the short-range ones with landline base stations) that was adopted by wireless phones because it was what every wired phone headsets on the market used.
The 2.5mm jack used on pre-iPhone wireless phones wasn't non-standard, it was a pre-existing, widely adopted standard for hands-free phone headsets established initially for cordless phones (the short-range ones with landline base stations) that was adopted by wireless phones because it was what every wired phone headsets on the market used.