The public

Me: "Hello, Taxi Service, Your pickup address please"
Caller: "I want a cab to 16 Elwood Avenue, Bar Beach"
Me: "Certainly, where would you like to go?"
Caller: "Oh.  I want to GO TO 16 Elwood Avenue Bar Beach"
Me: "Okay, well, I need to know where you are now, because that's where I send the cab to to pick you up.  You can tell the driver where you're actually going once he gets to your pickup address"
Caller: "I dunno, hangon, I'll just check. {pause} Hey Rob, what's the address here?"
 {Rob: wazzat? Caller: what's the address here, mate? Rob: Oh, hangon.  Hey Mike, what's the address here? Mike: 15 Smith Street, Mayfield East Rob: What?  Mike: 15 Smith Street Mayfield East  Rob: 15 Smith Street Mayfield East}
  Note that this has taken over a minute so far
Caller: "15 Smith Street, Mayfield East"
Me: "Okay, how many passengers?"
Caller: "Oh, hey, who's going?" {Rob: yeah, I'm going, and Shona and Linda, and Mike and err maybe Henry.  Mike: Yeah and Paul and Roger want to go too.}
Me: "So that's about 8 or 9 passengers.  You'll need at least two cars for that."
Caller: "What, can't we just fit in one?"
Me: "Well, taxis are just Holdens or Falcons, mate, so they seat four or five people"
Caller: "But My dad's got a Falcon with a bench seat in it and it seats six people"
Me: "Yeah, but a taxi has a driver, mate, so that's a maximum of five passengers.  And besides most taxis have bucket seats so if you want a five-seater car it might take a bit longer.  Can you find out exactly how many people are going so I can get you the right number of cars, and the right number of seats?"
Caller: "Yeah, hangon a bit"
  Let's wait another couple of minutes....
Caller: "Yes, there's 9 people going"
Me: "Okay, you're gonna need a five-seater car and a four-seater.  When the cabs arrive, make sure you fill them up completely otherwise you won't all fit and you're gonna need three cabs"
Caller: "Okay, thanks.  How long will that be?"
Me: "The taxis will be along as soon as possible" {HANGUP}

I don't have another fifteen minutes.  Policy is to state "your taxi will be along as soon as possible".  Basically we don't really have a clue.

Me: "Hello there, Taxi Service, Can I have your pickup address please?"
Caller: "This is Mr Yule at Tatt's Club"
Me: "Off to Merewether with one?"
Caller: "That's right"
Me: "See you next time, Mr Yule"

It CAN be as quick as ten seconds on occasion!

Fifteen Minutes Later

Driver: "Control how many cars have you got coming to 15 Smith Street Mayfield East?"
Me: "Just the two, you and 88"
Driver: "They're gonna need another two cars"
Me: "Righto..."

You learn not to question why.  And we started adding the "...your pickup address please" for obvious reasons.  A pity it didn't work 100% of the time.