The iPhone has a neat feature to reply to an incoming call with a prerecorded text. I find the standard texts pretty useless, and have them replaced with: Sorry, I’m busy. I’ll call you back in 30 minutes, plus variants for 2 hours, and tonight. I choose those because someone calling me typically does not want to know why I cannot respond, but when she can expect the call back. And I can explain the why in the phone call later, with more empathy.