Moan time. Or maybe "alternative way of looking at the same thing" time.

You often hear people saying "why not just pick up the phone?". "I like to get on a call with them". "What's wrong with speaking with them?"

I'll tell you what's wrong with it.

It's an interruption.

When I'm deep in work, an interruption of 30 seconds can knock me off my stride for 30 minutes or more. It takes time for me to get back to where I was, for me to straighten my head out again. I need to focus and to concentrate and that focus is easily lost.

But my work is mission-critical for some of my clients. So I need to keep my phone on just in case they ring me with an urgent problem (and they have multiple offices and I don't know all their numbers).

In that case, I want to be interrupted, because it's costing them money.

But for someone I don't really know trying to figure out whether they can sell me something I probably don't want ...

Your call is costing me money. Because I'm losing a significant amount of productive time.

That's why I don't want you looking up my number and just "jumping on a call with me".