Why are headphone jacks for computers and handsets differentdiameters than cellphones?
 

Because you have to then buy the vendors handset. Brand lock in.

Why are headphone jacks for computers and handsets different diameters than cellphones?
 

In article ,
"Daring Dufas: Hypocrite TeaBillie on welfare"
wrote:

Because you have to then buy the vendors handset. Brand lock in.

You asked and answered your own question, but your premise is wrong. The
headphone jack on both my computer and cellphone are the same size. Why
did you buy the brand you did if that was going to be a problem?