Mobile networks are requested to provide several added value services with different QoS levels. An efficient call admission control (CAC) is one of the strategic components that a network management policy requires, which defines how to allocate network resources to roaming and new users. We assume a hierarchical network architecture constituted of several cellular IP regions which may communicate each other accessing the Internet through a Mobile IP protocol. In such scenario, we demonstrate the importance of CAC not only in the ingress wireless points, but in the wired network too. An integrated approach to CAC is then proposed whose advantages are shown through simulation analysis.