I think WT was refewrring to the extremely rare case where someone in the US accidentally dials a terroist c`onnected number and gets a court sanctioned monitoring as a result of the accidental wrong number. I don't yet understand how the FBI or NSA will know it was a 'wrong number' without monitoring further.
I know that's what he was referring to. Of course they can't know. But either monitoring, with a court order if was an internal call, or other simple checks, would soon show them that it was an error, and the monitoring would stop.