The NSA has lied, under oath, to Congress concerning this DOMESTIC SPYING program and its capabilities. Not just once, but multiple times, over several years, and as recently as in March 2013, when the NSA chief point-blank lied to Congress when asked specifically about it. Don't take my word for it, hear or read it yourself:
NSA Chief Denies Wired's Domestic Spying Story (Fourteen Times) In Congressional Hearing - Forbes
Now, considering that they had no problems lying to Congress, what makes you think that they are telling you the truth when they say that they do not listen to domestic phone calls or read domestic internet communications?