You're absolutely right assuming that your problem has very close relation to the problem of different time zones. So the answer would be much like the answer to the other question. Here are some ideas I found useful for myself, but YMMV, as usual:
There's no silver bullet. Phone, email, and instant messengers co-exist specifically because they solve communication problems in different ways, so sooner or later you need all of them.
Let Them Know Before They Call You
I find sudden phone calls the biggest plague for effective communication. It should be eliminated at all costs. How? Let's think why your client is suddenly calling you. Don't they have other things to do? The answer is — because they worry you are no longer there, or you are behind your schedule.
Or, maybe, your client is a big company, and they have a dedicated person (call them Alice) responsible for communication with freelancers. But wait, Alice has their own boss (say, Bob). Bob may have entered Alice's room and asked, "hey Alice, what's up with our freelancer?" If Alice does not know, it's a big red flag for me.
Plus, she will certainly try to call you, and you wouldn't be ready for a report!
It's your obligation to prevent it, by making sure Alice knew what you are doing at any given moment. Don't let Alice to call you. If that happens exactly when you are sleeping, you are screwed, not Alice or Bob.
Schedule Your Communication
- Arrange weekly meetings. Make them short.
- Keep your task-tracking system updated, always.
- The same about source repository;
- Be proactive. Don't wait your client called you, do it first and use your preferred communication tool.
It's just a personal opinion, but I always let people know when I'm awake and when I'm working. I make it clear that:
- At working time, all communication tools are open;
- At the other time (but while I'm awake) they can reach me by phone, but it can happen I'm not answering or I'm not at reach of computer. Email is preferred;
- And yes, sometimes they catch me exactly when I'm sleeping. I call it the price for freedom. :)