It depends, as Roln stated. Here in the Portland, OR area, for example, every call sign is pretty much assigned, but the same officer could use different call signs at different times. I'm not aware of any local law enforcement agency *HERE* that actually assigns each person their own call sign.
For example, one particular law enforcement agency in Sacramento,CA
Nearly every single employee that would touch a radio has their own specific call sign. Even high ranking brass who do not assume patrol duties get radio call signs.
As far as patrol, each patrol officer has their own unique call sign that they carry each and every day. Unless, they are working a special assignment, such as a parade or local event. Then their call sign would reflect that particular event ( Parade 1, Parade 2 etc )
If the officer works overtime, moves to a new shift, a in a different area, then their call sign will change to one of many "spare" call signs, that would reflect that particular shift/area.
Some Depts. in California assign the individual a call sign. My dept. does this also.
2 examples are CA State Parks and Fish & Game. Most muni/county agencies, however, seem to assign the ID based on the assignment. Often, when the ID is assigned to the individual, not the assignment, the ID will be their badge # (as Parks and F&G both do).
Maybe this will help, as pointed out most officers have an ID number that is assigned to them. This is their Department ID that they use on reports,etc. What may happen is they log onto the radio like this : ID 1281, 10-8 as Alpha 21 till 23:00 hours. The officer gives his ID and the zone/call/assignment he is doing. When he calls in it will be using the radio ID, but the dispatcher will know which officer it is. The same goes for radios with ids' such as MDC, Modat, GE StAR and DTMF ID. Now depending on whether the radio is kept by the officer or picked up for shift, they still have the officer ID, and with a PTT , they can also have the radio id. In trunking systems depending on how its set-up they can be listed under ID, designation etc.
There are a lot of different options and variables...
most agencies around here are the shift + car number but my parish (county) S.O. deputies are assigned numbers that do not change....MP1 is the sherrif, MP2 is deputy sherriff, so on and so forth....state are troop + car number (F47 etc..)
ive been through i dont know how many towns in 10+ states and they are allll different
Logan Co. SO: "1" is the Sheriff, "2" is Chief Deputy. The rest are by seniority.
Normal PD: Last three of star.
McLean Co. SO: Dvision letter and number (Paul-2 would be patrol)
Bloomington PD: I think is like the MCSO
Macon Co. SO: Car number, I think. Except smaller cities (then it's like Warrensburg-1)
Well way back when, I worked for a small department at a small airport. My "call sign" was Police 3. The Chief’s was Police 1, the next senior officer’s was Police 2, and yet another one’s was Police 4. Sometime later we all got new badges that had numbers 801-806, by this time I was the ranking officer, just under the Chief, and our call signs reflected our badge numbers, so mine was then 802.
So, as it has already been stated, it mostly depends upon the particular agency you’re monitoring at the time.
Here in Hamilton County, Ohio the agencies dispatched by the county comm center mainly use the following format:
Where the first number and letter indicate the agency, the next number indicates the shift, and the last number indicates the beat or assignment (i.e. canine, traffic, etc). For example: 9L26 is a Colerain TWP car on second shift covering beat 6. Some of the smaller agencies will not use the last two numbers like shown and just assign them to individual officers based upon seniority. For example: 5X30 is a Xavier University part-time officer.
Now the City of Cincinnati uses a four digit id where the first number is the district, the second number is the shift, the third number is the beat, and the fourth number is the zone within the beat. Of course this has some slight variations as well.
PD here uses ID's that reflect shift and district.
Example is 'Charlie 5' is third shift, district 5. they used to use their badge numbers many years ago. The traffic guys, detectives, Sergeants, Lieutenants, Captains and the chief all have their own assigned numbers. '3 Lincoln' for the third Lieutenant in seniority, ect. Captains are ID'd by division; 'Paul 1' is the Captain in charge of the patrol division. Now, if someone wants a particular officer, they call each other by last name. If the officers are on special details, they use their 4 digit personnel number.
Sheriff's Department and State patrol use their badge numbers, so it is easy to place a name with their numbers, and keep track of them.
At the agency I dispatch for full-time the radio designation is based on what patrol zone the officer is in. We have 9 patrol zones, hence we have Unit 1 through Unit 9. The more senior officers work the same zone every shift. The younger officers are rotated through the busier zones to gain experience. We work 2 on/2 off rotations so they'll usually be put in a busy zone their first shift and then in a slower zone for the second shift.
The agency I dispatch for part-time has no patrol zones, just 3 patrol units on the road. They use the car number they're driving as their radio ID. Each officer is permanently assigned to a particular patrol car. Most of the guys will use their assigned car ID even if that particular vehicle is out for maintenance.