A number of years ago the feds busted the then-Mayor of Waterbury, CT, on a juvenile sex offense using that technique. They were actually secretly investigating him for alleged corruption when, in the course of the investigation, they intercepted a series of cell phone calls (or text messages, or both) pertaining to his efforts to get a mother to make her two very young daughters available to hizzoner for ... ah, well ... for certain "services."
The feds, to their credit, chose to blow up their corruption investigation and bust the creep for the attempts to engage in juvenile sex. IIRC, they were able to assert jurisdiction because some of the cell phone calls were made or received from the western part of Connecticut, and bounced off towers in New York state. Ergo, "interstate communication."