This means that every time a person moves and their smartphone connects to other different antennas, these movements can be tracked. In cities there are a greater number of antennas than in the countryside, which makes it easier to find a device. Furthermore, if it is connected to several antennas at the same time, you can know more exactly where it is, since it is enough to see the areas in which this intersection exists.
If the police obtain permission to intercept communications, for which they do need judicial authorization, they can use SITEL. It is about the acronym for Integrated Telephone Interception Systemwhich means that, after the operators give access to the authorities, the latter can listen to the conversations and know the location from which the calls are made.
In case the criminal turns off the cell phone, it will be more difficult to locate, since you can only know its last location, as well as track it again if it turns on again at some point. Notably