An out-of-band basic access signaling (BAS) protocol is introduced for use in heterogeneous wireless networks. The BAS protocol enables a mobile terminal to communicate with an agent in a fixed network through any radio access network chosen by the user as the basic access network (BAN). The agent uses information on the location of mobile terminals and the availability of RANs to decide which RAN to use, taking the. user's preferences into account. This protocol was implemented in a demonstration system using existing radio systems and standard Mobile IP. Separation of the signaling path from the data paths was found to save energy and facilitate handover between RANs.