A method, system, apparatus, and computer program can provide scheduling of direct to direct communication by a high speed packet access base station. The method, for example, can include obtaining a direct user equipment communication toggling message. The method can also include interpreting physical layer signaling on a first frequency of a first radio system based on the toggling message. The method can further include scheduling a direct user equipment pair on a second frequency of a second system based on the interpreting. The toggling message can include a triggering message to initiate direct user equipment communication or an exit message to terminate direct user equipment communication.