The network capability and the state of the terminal are two factors that should be emphatically considered in vertical handoffs, while user willing based selection could always leads to a disastrous result such as communication interrupt. 网络性能和移动终端状态是垂直切换中必须要着重考虑的两个因素,而根据用户自身意愿进行网络选择往往会造成通信中断等灾难性的后果。