"Yep! Constantly out of time and place, aren't we?"
It seems from what the Doctor's saying that he can tell his other self is here. That's not a surprise; after all, the Doctor had told him before that he'd know if another Time Lord was around. Guess it works even with a half-Time Lord/half-human.
He laughs and hangs up the phone as the Doctor comes sprinting, arms spread wide and ready for a hug.