Unless you've been on the receiving end of a story pitch, you likely don't appreciate the urgency of being succinct in those interactions.
Having been on the receiving end of such pitches for about 20 years, I can assure you that the goal ought NEVER be selling the reporter, editor or producer on a story--that's asking too much, too soon.
When I reach their voicemails (the usual scenario, as most don't pick up the phone), I leave a brief message with the gist of my call and a heads-up that I’m about to e-mail more detailed information.
Those e-mails all lead with the phrase “Following up from the voice mail I just left for you…”
When reaching an individual directly, my first goal is to pledge brevity. How I typically start: “Are you on deadline, or is this a good time to talk for 30 seconds?”
Such a courtesy signals that I know their world—and I am not about to waste their time. Saying “30 seconds” is intentional—when people trot out “Do you have a minute?” they usually don’t mean 60 seconds, but upwards of 10 minutes.
Now, if someone starts to engage you and you stay on the phone longer, that's great. But it has to be their call.
Your objective in calling is not to “close a sale” as they cheerily promise to crank out a story. Rather than closing anything, you want them to open up.
Warm ‘em up to the idea that the e-mail you're about to send is worth serious consideration, instead of the reflexive tap of the DELETE key.