The set of tones you hear at the beginning of a call is to activate various alerting systems. Pagers, walkies, station base sets, etc... so that the personnel know they have a call.
Each station usually has a set of tones.
If you're inquiring about Anne Arundel county, we're a two-tone system so each set of high-low or low-high tones is a different station. You'll also hear a different tone as the final tone for the dispatch; the length of time, pitch, and if it "beeps" or not all mean different things.
The rest of the numbers you're asking about I'll go by example here; this is how it's done in AA County, and the other counties are similar but close. AA doesn't give times with their dispatches, and some counties don't give cross streets or map coordinates.
Here's a sample box that happened the other night. Should be OK to post, as no personal info was included and it turned out to be false anyway.
Water Rescue Box, 19-6. Engine 171, Paramedic 17, Squad 12, Truck 23, Fireboat 61, Fireboat 35, Divemaster 1, Dive Unit 30, Special Unit 6, Boat 6, EMS 1, Battalion Chief 2 respond for vessel capsized in Whitehall Bay. Cross streets of Skidmore Road and Holly Beach Farm Road. Coordinates 21K8 respond on Kilo.
Needless to say, this one took a bit to tone out...
The "Water Rescue Box 19-6" is what you were referring to, and it refers to the "box area" for the call. In most counties (all of them, pretty sure) in Maryland, all fire departments and EMS units are consolidated... so medical calls are dispatched into box areas just like fire calls. This is a specific area of the station's coverage, and only the station and the dispatchers really know which box area is which... it's on maps kept by each station.
There are different types of boxes...
Medical Box - your typical medical call.
Rescue Box - a firefighter and medical call. Vehicles w/ entrapment, etc.
Water Rescue Box - firefighter/med call. Any amphibious ops.
Local Box - a fire box... smallest response, usually 1 engine.
Still Box - a fire box... small response, usually station or station + 1 other piece.
Box - a fire box... larger response, small structures etc.
Commercial Box - significant structures, commercial buildings... this usually pulls a battalion's worth of apparatus.
HazMat Box - Hazardous Materials response.
The second part is the apparatus due to respond, in the order of response. The above call is an odd example because the box area is actually not totally correct for the call (notice it's a 19 box, but none of 19 was dispatched). On larger boxes, you'll hear "first due" units, "second due" units, etc. referred to, as each one will have a different function on the fireground. On significant EMS calls, it's the same for any additional medical apparatus.
The third part is the nature of the call, with as much info as the dispatcher has.
The fourth part is the location of the call and the cross streets so they can locate them on the map.
The fifth part is the map coordinates. Most counties use ADC map books which are broken down into pages and grids... 21K8 is page 21, inside box K8 on the map.
The last part is the tactical channel to respond on. AA County refers to theirs by phonetic letter; some counties have theirs numbered.
Most areas surrounding us use the same basic dispatch format, with some things added or subtracted due to equipment variance or SOP.
Hope this helped... please ask any other questions you have as we're all willing to help you! Any of you FF's and comm types please correct me if I'm wrong.
