"Pager" Tones
First, you have to realize what the "tones" are for.
Unfortunately, that varies by department.
TFD uses the 5 beeps (same pitch) as an "alert" tone - just so that the guys can "tune out" a call in another part of town. Traffic that doesn't start with the beep beep beep... is just that, traffic. When you hear the beep, listen up, until you DON'T hear your unit in the list responding. But that's all it's for.
Now, TFD does have some other things they do electronically, both over land lines and on the radio via a data channel. They get printouts of the call (via landline) if they're in the station. And the trucks have "data boxes" that can update their status via radio to the dispatchers graphical display. But those don't use "tones" that you hear. The dispatcher can also remotely open the bay doors (also via landline). That's why you hear things like the service truck asking main to "hit the drop for station 'x'". He's just being let in.
On the other hand, when I was a volunteer years ago, we had pagers. Each FF had one, and they were programmed by station to stay silent until your station's "tone" set it off. It's the same priciple as PL tones to break squelch, but in this case they're audible. It was an audio "clue" that you were supposed to be moving (if you were listening on the radio or a scanner) and also they turned the pagers "on". Handy at night, since you could sleep and not be disturbed by a car wreck for another station. The pager stayed quiet until it was a car wreck for YOUR station.
What you hear around here is a combination of these. Some departments use alert tones, some don't. Some use pagers for volunteers (either full vollie or part paid) or for off duty recalls). Some use both (Catoosa?). Some might even use them to open the bay doors ala "Emergency 51" (the TV show), but that I don't know.
I suspect that Supulpa and BA use land line for data and/or bay doors (if at all), and what you're hearing elsewhere is for the part-paid departments, where the paid guys roll the truck, but the vollies respond to the station to be ready to roll the second one if the paid guys want manpower.