You needn't feel like a d*ck. Just realize that when people call you or text you it is on there time; however, replying does not need to be on their time - but on your own time. I have found if I forcefully and succinctly communicate that - it works.

I deal with it this way: The people I care about I frankly say "Look, I only prefer to communicate at certain intervals during the day because I'm usually in flow or focused. Please text and call, but realize if I don't answer it was because I was in that state. Sometimes I come out shortly, sometimes it is a few days".

Texts, calls, etc go unanswered until I'm ready on my time.

You'll have to tailor to the person though... some extroverts forget everything they read and/or have low impulse control, some introverts forget everything they hear.