This isn't any one specific agency in Clark County ... it's the MAIN number for the entire Clark County administration, so the purpose could be any number of things.
>> it's the MAIN number for the entire Clark County administration <<
Are you aware that CallerIDs can be spoofed?
In other words, the bad guys can fake what appears on your phone's CallerID!
Example: Your CallerID may display your bank's name and number, but the call may really be from a criminal scammer, with a completely different phone number.
If you Google "caller id spoofing", you will see dozens of companies that offer that "service". It is quite easy for the bad guys to spoof, too!
More info:
https://www.fcc.gov/consumers/guides/spoofing-and-caller-id