—In this paper we study the performance of the Ambient Networks (AN) access selection architecture. We consider heterogeneous wireless networks, where mobile terminals (MTs) own multiple radio technologies and need to remain connected while on the move. We would like to provide the MTs with seamless IP services, such as video/audio streaming, so that changes in their point of attachment will not affect the experienced streaming quality. In the first part of this paper, we present the AN architecture for access selection, along with its functional entities (FEs), their interrelations and the algorithms that are to be run within each FE. Hence, we describe our ns2 simulation framework and detail two simulation scenarios. We finally discuss, through extensive simulation results, the effectiveness of the AN architecture in reaching the above goals.