What's all this about you have to have a premium subscription to search the frequency database? That is most certainly NOT TRUE!
Here's the search results for 858.5375 in RR's Arizona FCC Search
Looks like a private SMR to me.
Let's try to remember that we were all newbies once and a lot has changed over the last 30 years when I first was introduced to scanners. Today's scanners have gotten seriously very complicated little beasties to program and operate and the learning curve is steep. Let's not drive away new scanner hobbyists by giving them false information and treating them like a nuisance.
Airscan, if you have questions you can PM me anytime and I'll do my best to answer.