Once upon a time (at least thru the 1960s) the FCC call letters issued in the land-mobile service followed a little bit of a scheme that would enable one to have a reasonable idea of the geographical origin of a station heard. It all hinged on the second letter of the three prefix letters with them very often corresponding to the ham call areas.
ham call area: 1 2 3 4 5 6 7 8 9 0 2nd ltr in pfx: C E G I K M O Q S A
Of course, with some of the less-clearly enunciated IDs from the fire/police/business dispatchers/mobiles it was often difficult to distinguish the B/C/D/E/G/V, F/S, etc. That's why the Morse-coded tones were more reliable (if not too fast or made using a defective mechanical-keying device!) Many two-way services now have their IDs encoded in a digital burst at the beginning of each transmission.
This might remind some of the 1958-62 FCC use of their Radio Inspection District number as part of the prefixes for the 27-MHz Class D CRS call letters. Here in south Texas that had 9W#### (later 9A and 9Q). Soon the emerging nations of Africa noticed that these were the same as those that the ITU had allocated to them! To rectify that, new/renewed licensees were then given a three-letter prefix beginning with K followed by four digits. In this the 3rd letter of the prefix was keyed to the 24 FCC RIDs - with this area ending up with things like K-T####. By the mid/late 1960s that middle letter (changed yearly or after 9999 was reached) was already up to around Q and that system soon seemed doomed to falter. In the mid 1970s those operators in too much of a hurry to use their equipment before the "in-box" FCC Form 505 had been sent in with $20 and answered were permitted to concoct their own "temporary" call signs incorporating, of all things, their name initials and ZIP code! Lots of K---78228 soon in these parts. The FCC eventually solved the "problem" by simply not bothering to issue/renew any more licenses/calls for the service. Anarchy had won.