Patent ID: 7519365
Filing Date: 2009-04-14
Classification: H04W

Abstract:
1. A method for a radiotelephone to search for higher priority public land mobile networks comprising: camping the radiotelephone on a cell of a visited public land mobile network and registering on the visited public land mobile network; uniquely identifying the cell; searching for public land mobile networks with a higher priority than the visited public land mobile network while registered on the visited public land mobile network and camped on the uniquely identified cell; storing a history of those frequencies found during the searching step, while camped on the uniquely identified cell, that are not of a higher priority public land mobile network, the history being associated with the uniquely identified cell; periodically searching, at a slow rate so as not to consume much battery power, for higher priority public land mobile networks in all radio access technologies and frequencies supported by the radiotelephone; and if a history already exists for the uniquely identified cell, then updating the history with any new frequencies found that are not of a higher priority public land mobile network to any previously found frequencies in the history.