I once got a phone call on a day I'd set aside to dye my hair - as in the dye was mixed, the gloves were on, and I answered the phone ONLY because I hadn't started spreading the dye in my hair yet.............and this was before Caller ID, so I had to answer it to learn who it was.
The phone stayed off the hook until I had the timer started after getting the dye in my hair, at that point.
I no longer dye my hair - last time my scalp itched, not a good sign - but I have been known to check the phone display to see who it is - then decide what to do (relatives & friends - I usually answer - businesses can leave a message).