Here's the thing, though: phones disrupt without being useful because you have to answer there and then. With the very fast letters you're allowed to think, you're allowed to wait before you answer, and you can attach files, pictures, anything you want.
What's really funny is how people insist on having a meeting about every little thing. Endless discussions, new meetings, people brought in to make decisions, more meetings. That very fast letter is a better option.
Unless, of course, you're talking to your mum.