The integration of WLANs and CDMA networks has recently evolved into hot issue. We propose a vertical handoff algorithm between WLAN and CDMA network. In this algorithm, a vertical handoff is classified into handoff decision making and MIP (Mobile IP) registration process. Then, a handoff initiation is decided by the received signal strength (RSS). To reduce the unnecessary handoff probability, we consider a handoff initiation model based on the criteria of RSS. As a mechanism of network selection, we also propose a context based network selection and the corresponding algorithms between WLAN to CDMA network, based on wireless channel assignment. We focus on a handoff initiation criteria which uses both the RSS and the network selection method which uses context information such as dropping probability, blocking probability, GOS (Grade of Service), velocity. As a decision making criterion, velocity threshold is determined to optimize the system performance. The optimal velocity threshold is adjusted to assign available channels to the mobile stations. The proposed scheme is validated by computer simulation.