How Carefully We Proceed

I have an idea of what I'm going to say to this person when I call him tomorrow. Unless I get a voicemail, at which time all my talking points will be useless and I'll stutter out a message that sounds like, "Hi ... I'm, um, Dave, you called me - Dave Richardson (it's important to remember that he might know lots of Daves and I should use my last name) - uh, returning your call from the other day. I was just, uh, wonder what you thought of my ... Oh, I didn't tell you about my film. Yeah, why don't you call me back - when you have free time - and we'll, um, I dunno, talk more. I guess. Yeah. My number is xxx-xxx-xxxx, but you already have that, so, um, I'll talk to you later."

How do I know that's how stupid I'll sound? I've used phones before and I've had to leave unexpected voicemails when I had anticipated speaking to someone. That's not as bad as trying to get a voicemail and winding up talking to the person, though. Much more awkward.