Thank you. But the next sentence reads " It is also run against a large set of what are known as “dirty numbers”—telephones linked to terrorists either through American signals intelligence or information provided by foreign services. Even the Libyans under Qaddafi turned over huge stacks of dirty numbers to us."

So that seems to correlate with what I am saying - they have some flag generated offline that they use as a marker to find something online.

Oh, they definitely do both, I'm not disputing that.