NSA Surveillance Program

I am having a problem understanding how the NSA surveillance program is suppose to work; or how it is suppose to protect us.

If the program records all phone calls, then the NSA knows that my number has called your number 9 times in the last week (remember, we were told the NSA doesn't know what was said).

So the NSA now has millions of millions of recorded phone calls; so what do they do now?  They can't manually look at them, so a computer must isolate certain numbers as suspect.  How do they ascertain which are those numbers?  If the NSA knows of a suspected terrorist, OK then, record all the calls that person makes.  But, unless that suspected terrorist calls me there is no purpose in recording my calls.

The only purpose of the program then becomes one of determining who I am calling; an adult book store or a  socialist party magazine and so on.  But what does that have to do with stopping terrorists?