There used to be a very handy Android app, now booted off the Google Market, called "GSM Spy Finder" which worked on MediaTek SoCs.
edit: if you've ever spent some time sitting on a plane (non domestic) and your phone was on during the time-window when boarding is ongoing and just before the aircraft taxis to the runway, then there is a very good chance that you've connected to one of these before. It's a way to match known cell numbers of individuals where an arrest warrant has been issued (or otherwise individuals that are monitored) against actual passengers phones (who might be traveling with a fake ID). If somebody on your flight was ever lifted off the plane by LEA (but obviously has made it through security into the plane) they are very likely the target of such a dirtbox intercept.
You'd think fugatives won't bring their phones with them, turn them off unless absolutely necessary, or use burners.
in reality huge number of arrests are made due to incredibly dumb mistakes (and not because LEO's used some super newsworthy hack).
Unlike them, I was never caught and have no record. A lot of that is down to lucky, obviously, but the ones I know of who are still active and not in prison do similar things (burners, never have a device on them if possible, rotate burner SIMs constantly, use encrypted messaging, etc.).
Anyway, its been years, but it's a lot less stressful to be sober and law abiding!
Just anecdotal evidence, however, while I almost never got false positive alerts from this app (once at the arrival of an international flight), the one time it triggered a notification, it was in a highly probable situation.
Communication between our devices and these base stations being so opaque (closed-source baseband processors/OS not helping there) and sensible, I'm glad these projects exist and I just installed this one, blaming myself for not doing so earlier.
It will reveal a catcher nearby if you are already familiar with the local area.