Is it permissible for the fiancé to talk with his fiancée over the phone and keep her pictures, knowing that the marriage will be delayed for six months?

Addressing the fiancée over the phone has been answered previously. As for keeping her picture, it is not permissible for two reasons: First, she is still a non-mahram. Second, keeping pictures is not allowed except out of necessity or an unavoidable need, due to the Prophet (peace be upon him) saying: "The angels do not enter a house in which there is a dog or a picture."