At first, talking on the phone was annoying. But now that's no longer the case. I only accept orders by email and also assign them that way if I have something myself. If you don't feel like doing that, or think you can discuss everything on the phone, you just have to find someone else who sees it that way. I also use the time I answer the many emails as a mini-break. For many people it may make more sense to deal with emails at set times (eg in the morning), but I almost always have my email program open and then reply as soon as it suits me.
Imagine this as if it were a natural Pomodoro timer (see next point). Every fifteen minutes thailand whatsapp or so, new emails arrive, which I then use as a mini-break for myself and answer quickly. Long story short: If you don't have a secretary, you should set up your communication so that it fits your own workflow. You don't have to be available via chat, phone or in person if you don't want to. If, like me, this just distracts you in your day-to-day life, then set up your business so that this annoying stuff is no longer necessary.
5. Some need aids As I said, I use answering emails as a natural Pomodoro timer. What is that? The Pomodoro technique essentially says: work hard and concentrate, but take lots of short breaks. Typically 25 minutes, then a 5-minute break and so on. This is supposed to help you be particularly effective and, above all, to remain effective over a longer period of time. There are a number of apps for this and many self-employed people find it helpful with their own time management.