A communication device locates a preferable wireless service provider in a multi-service provider environment using a frequency or frequency band search schedule. Initially, the communication device registers with a less preferred service provider in a first frequency. While remaining registered with...http://www.google.com.tw/patents/US8081973?utm_source=gb-gplus-share專利 US8081973 - Method for selecting a preferable wireless communications service provider in a multi-service provider environment
