Embodiments of the present invention direct a mobile device to communicate using a particular radio access technology when multiple access technologies are available. Many mobile devices have the capability to use multiple radio access technologies. The process of providing access guidance to the mobile device at a point in time is described herein as a radio access discovery and selection event. Embodiments of the present invention may complete the event using only two messages. In one embodiment, the first message is a SIP OPTIONS message communicated from the mobile device to the access guidance component. This message identifies the mobile device and the mobile device's present location. In one embodiment, the location identification information is communicated within the PANI header. In response, the access guidance component communicates a preferred radio access technology within a SIP 200 OK message.