Anything he reads is from instant feedback or twitter. He's usually very good about crediting it, even if it's just "some listener writes". I don't think Ant credits all the lines he gets from Paltalk though.
Compared to the WNEW days, the use of listener material declined substantially. I remember hearing the crinkling pieces of paper after O&A read an Instant Feedback that Stinky or Ben would hand Op or Ack.
And let's be fair: The Opester is good for a hysterical line every once in a while on his own.