I can't see how that wouldn't work just like any other dialogue, unless by "third person" you mean that you're out of your character's head and the narrator can't hear the other end of the conversation. In that case, I think that the readers don't have to hear the dispatch and the woman's part of the conversation is enough for them to gather what's going on.

Also, if you want to know what a 911 call looks like, call them from a payphone and pretend that someone's been shot. That's what I did, but I'm not from the US and I think that prank calls like those are illegal, so, er... you might as well stick with what you have ^^