Here in Colorado the CSP will usually `announce' either 10-99 or `possible' 10-99 depending upon what type of info they may have, EI: Definite Warrant or Possible Warrant but we sure could use more info from you, and then will add `Code 6" to find out if the `subject' is present or where they can hear what they have to say. (I'm actually listening to CSP at this very moment and the conversation was Dispatch, "3Adamxx 10-99, pause, Code 6." 3Adam xx, "Code 6 go ahead." Dispatch, "3Adamxx, and then the warrant info.") Sometimes they'll broadcast a tone and announce 10-99 in `such and such location' or maybe announce a trooper's call and say "In the blind 10-99." All of which I suppose could be said to serve, too.
Weld County SO, OTOH, seems to be a tad bit more `relaxed' about it and the officer is usually the one who initiates any warrant or other info by asking for it. (The last time I heard a county dispatcher `volunteer' the info before the officer replied I could hear the `subject' `raising a ruckus' back in `the cage' in the background and the officer requested that there be someone down at the `NJC' [Read Jail] to help him get the `subject' in *and* a *very* `curt' `Thanks alot!" Turned out that it was the dispatcher's first night on the job and had just taken over the console on a shift change and the previous dispatcher hadn't told her that the `subject' was probably already in the back and to wait for the Officer to request further info before `volunteering' it. My `step-sister-in-law', who happens to also dispatch out of the same center, told me about the rest of it a couple days later and said that *both* dispatchers got, as she put it, "A *good* `talking to' that they'll have a hard time `living down'." {VB GRIN!} She also said that it took 4 other Officers to get the `subject' out of the car and into booking! {YIKES!} Since then some of the dispatchers will use `code' and all of them pretty much wait until asked.) It's been quite a while since I've heard anything like, "Is your mike clear?", "Are you clear?", or any other variation along those lines.
Back in my `mis-spent youth' it was SOP for the dispatcher to always check the `records' but not air anything beyond an acknowledgement until we asked specifically for it. IE: We'd call in a DL and/or plates, the dispatcher would ackowledge, then as needed we would then request any info. If there was anything beyond `clear' the dispatcher would `call' us and depending upon the situation we would either reply as `standby' or `clear go ahead'. *If* it was something that warranted our `dropping' what we were doing the dispatcher's had one of those `front counter bells' type setups that they would `ring' before giving our ID and we would then acknowledge and either, as quickly as possible, clear up what we were doing or `cut loose' whomever we had and `start beating feet' so to speak. If it was a case of `extreme positive entropy in hades' they had a `howler' they'd transmit and then follow up with what the situation was and everyone who was *anywhere* even halfway close would *immediately* `drop' what they were doing, with a very few exceptions, and start `beating feet'. There actually were a couple times when *I* had to almost `throw' a `perp' out of my vehicle to answer one of *those* calls! (Fortunately *both* of those times it was something that I could easily go back later and finish up. [And *one* of them just the `act' of originally having the `perp' in the back of the car already to `take the ride' and then almost literally `throwing' him out made such an `impression' on him that after coming back later and hauling him down to the station the DA decided that he probably wasn't going to try it again and let him go *and* we never had any more problems with him after that! An early example of `scared straight'!? I *do* know that the last couple times I've run into him over the years he always thanks me for how things went that night. {GRIN!}])
It seems that there are quite a few different, as many as there are agencies and officers it seems, ways that it can be done and for us `scannists' the `best?' way to figure it out, besides discussing it here, is for us to just keep our ears `clean' and `open'. {GRIN!} It would be `nice' *if* there always was a specific code used nationwide but, given that it's just part of `human nature' to `do it our way', I suspect that it is something that'll never really ever happen. Besides... Just think of how boring it would be if we *didn't* have to figure out `regional?' differences and `quirks'? I dunno about you but to me it'd be almost like having everyone dressing, having the same `hairdo', wearing the same glasses, speaking with the same `accent' and `inflextions', ETC. just like everyone else. *Boring*! (Not to mention that all the `perps' everywhere would *also* end up knowing what was what, too. Which would probably make for some pretty `hairy' situations a lot more times than would be `wanted?'!? [While there are some `perps' who definitely aren't the `brightest candle in the candelabra' there are plenty more who are at least `average candles' and would pick up on what and how things were said. {WAN GRIN!}])
Just an `Olde Fart's' 2¢ worth. {GRIN!}