It means, the sniper told them "Go and get yourself a shortwave transciever, tune it to this number on the dial, and sit there until I start talking. At that point, I'll ask you a series of questions, the answers to which are in this note. When you answer them correctly, I'll provide a routing number to a Swiss bank account. You'll transfer X amount of money into that account. Then you'll never hear from me again. Got it? Thanks."
See "Proof of Life," starring my favorite famous conservative, Russel Crowe, for where I came up with this theory.
The "we're unable to do that" translates roughly into "um, our resident FBI / NSA consultants said we can't do that, since you could be transmitting from anywhere on earth and we can't triangulate it, so we can't trace it, so why not call this insta-trace 800 number instead?"
Unwise move on the part of the police. Somebody else will probably get shot because of it. It's like a hostage situation, where a hostage gets executed every time a demand is refused - only the hostages consist of the citizens of three states.
I've ranged from a lone-nut theory, to an Islamic terrorist theory, to now a master-assassin theory. This guy's probably either one of our own assassins gone Ronin, a Serb or Russian assassin, or some professional sniper graduate of the School of The Americas (Columbian or Peruvian come to mind). With this much heat, it'd be damn near impossible to disassemble a rifle within seconds, and walk away with it, without being seen - unless you've been thoroughly trained to do so.
Are you suggesting they meet his demands?