I have unfortunately done it I think three times, every time because I'm trying to turn the volume up or down quickly.

the first time I cancelled the call, they called back and I explained.

second time, I stayed on the line to explain, which they appreciated. this time I turned the feature off.

third time was on a new phone and hadn't disabled it...

I don't remember if iphone switch the volume button side between generations, but on Android it's not consistent model to model..

it's a great idea for sure, but it's easy to do accidentally if you confuse volume for power.