Okay, we're not usually ones for sports metaphors. But follow-through--you know, when you continue the arc of your swing or your toss--can make a huge difference in whether you get the press coverage you hope for.
By continuing the arc of a conversation--the one you began when you sent music or event details or some other fodder to a journalist you're hoping to reach--you are more likely to see results. Stop mid-arc and your results will suffer. Even if you are busy or overwhelmed with other tasks, it's crucial. It's really hard to rebuild momentum.
In short, when you're in active press outreach mode, answer your phone. Especially if you're the press contact for your band or project. Especially if you're two weeks out from that big show. And especially, especially if you have an interview time set up.
If you do miss a call--we all do--call back swiftly. Be civil and be ready to talk.
In short: pick it up, or drop your chances of getting coverage for your music.