Emails: permanent written record I can refer to later
Can reply in my own time
Low labour
Low resource use
Phone call: Times/dates mentioned will be forgotten often
Active demand of time
I don't pick up because that phone number looks weird but also my phone's vibrate function is weak
High labour
High data cost per information
My shrink's office seems to want to keep billing information and past/present appointments secret. (This also seems to be worse in local industry, everything has to be a meeting instead of a two line email)
it varies from place to place.. in my last job it was hopeless trying to keep up with the never ending flood of bullshit emails so i didn't even try
in my current job i can keep my inbox completely clean at all times