Is telephone expense a fixed cost or variable cost?

It depends on the plan you have. Mine is a fixed expense because long distance, texting and so on are all unlimited. It costs a little more up front but if I have an emergency and need to make a lot of calls that I don't normally make it doesn't cost me extra. Without an unlimited plan I would have to pay for each call so if my calling increased for some reason, my bill would fluctuate.