Learn not to depend on the other person's reactions such as vocal tone or body language to decide on how to
re-act. The problem that most guys have face to face is having that type of defensive interaction with women. Ever wonder why some guys can't seem to escalate? It's because they're waiting on her to make a forward progression either verbally or via body language so that they can follow it; totally defensive and reactionary.
Learn to drive the conversation offensively and have her follow
your lead, she will do it readily if she's interested. Since you are in the drivers seat it's easier to lead whether or not you are in person or face to face. You can take things in any direction you'd prefer and it would be up to her to follow you.