A lot of wireless standards are proposed to satisfy diversified requirements for mobile users such as IEEE 802.16 and IEEE 802.11. It is feasible to integrate heterogeneous networks to provide complete wireless services. Several strategies were proposed to realize seamless handoff in the heterogeneous networks; however, most of them were only designed to meet system performance or individual QoS requirements for mobile users individually. In this paper, we propose an individual and system views (ISV) strategy integrating the individual view (IV) and system view (SV) to provide the proactive method that can choose the Internet Service Providers by MS and make the deliberated vertical handoff procedures with high throughput of UGS and call management services in heterogeneous networks. Our proposed strategy provides a complete procedure to determine the target network that has not been offered in most papers. Moreover, according to simulation results, the proposed ISV strategy is able to earn significantly lower handoff times than IV and SV and provide stable wireless network given high precedence for UGS traffic and real-time services.