If your ex still calls you and wants to speak to you even with a girlfriend, it probably means that he still has feelings for you.
But still, that is not a sign that he wants you back or that he even will come back. But this article, as you have seen, is about maximizing your chances of getting him back if you really want him back.
Even if he did leave you for a new girlfriend, it doesn’t mean he won’t be back. He might well be in a rebound relationship.