Have a conversation with your baby, face-to-face!  Let him learn the patterns of conversation through turn taking.  You say something, maybe ending with a question, and then pause to let him have a chance to “say” something.  All that babbling is him talking to you!  Even if he isn’t babbling back yet, still pause before talking again.  Engage in conversation as long as he is interested- aim for 10-15minutes.  Soon, you’ll be amazed how quickly he understands turn taking!  He will just love spending quality, focused time with you just talking!