If you are given the presumption that you are talking to a person, it doesn’t instantly follow that you are talking with the person. The person may not be able to respond, maybe because he chooses not to respond or because there are communication barriers that hamper the process.
If your interpersonal communication fails, it switches from being inter to intra. When there is no feedback involved in the communication process, there is still communication. Intrapersonal communication, that is.
As how they quote it: It is a not a one-way thing. It take two to tango. But actually, they are referring to effective interpersonal communication. Spot this.
John: Hey! How are you?
John: Nice talking to myself.
Again, there’s still communication. Just awkward.