https://www.quora.com/q/techinsider/The-NSA-phone-spying-program-exposed-by-Edward-Snowden-didnt-stop-a-single-terrorist-attack-federal-judge-finds?ch=99&share=6c3ad8ea&srid=9CvSA

Jim Bell's comment:

However, I wonder if that this phone recording was ever used to backtrack to get other evidence.