That is the point I am trying to get to without giving away specifics. The reason you see homegrown communications networks in Mexico is because it is trivial for the DEA to identify members of smuggling operations by way of cell phone TTPs. DEA obtains both explicit and unauthorized access to cellular networks in foreign countries. At that point it is a pretty trivial pattern matching problem which allows you to identify persons of interest and track them going forward.
They do use large scale "direction finding" to identify radios used by smuggling operations, but that is primarily targeted at boats with higher power transmitters.
As I stated earlier, it does make sense to deploy shadow comms infrastructure along the southern border (and northern border of Mexico). Detecting a bunch of cell phone traffic in a completely remote area nowhere near any official border crossings is indeed hugely suspicious. And the cartels do set up their own infrastructure there.
What doesn't make sense is deploying infra in the vicinity of major cities. There's plenty of benign cell phone traffic there, and this kind of pattern matching is not viable.
That is the point I am trying to get to without giving away specifics. The reason you see homegrown communications networks in Mexico is because it is trivial for the DEA to identify members of smuggling operations by way of cell phone TTPs. DEA obtains both explicit and unauthorized access to cellular networks in foreign countries. At that point it is a pretty trivial pattern matching problem which allows you to identify persons of interest and track them going forward.
They do use large scale "direction finding" to identify radios used by smuggling operations, but that is primarily targeted at boats with higher power transmitters.