In future wireless communication networks, seamless handoff either by vertical or horizontal is an important issue in radio resource management. For a vertical handoff (VHO), each candidate network is evaluated as a function of multiple attributes such as available bandwidth, delay, data rate, and cost, etc. However, the variations of these parameters and distributed VHO decisions might cause the instability of VHO decisions, which is inefficient in utilizing network resources due to frequent handoffs. In this letter, we propose a service history-based VHO algorithm to reduce unnecessary handoffs and call dropping probability in addition to QoS parameter considerations. Simulation results show that the proposed VHO algorithm outperforms existing algorithms.