I think the argument I wanted to make was that the people NSA claim to be after aren't using your typical contractual phone plans, since OP was suggesting they should simply track call logs.
Sure they used pre-paid phones as well as pay phones, hotmail and were still using coded and hidden messages.
Today they'd be using that steganography over cryptography.
Few sources:
http://www.cbsnews.com/2100-205_162-4985597.html
http://www.schneier.com/blog/archives/2009/11/al_qaeda_secre...