| 摘要 |
The System Select feature provides user selectable modes of operation in a mobile communication station, which allow certain fall-back options when a preferred system may not be available, but still steers the bulk of the system selection operations to preferred systems. In a first user selected mode, the mobile station scans for a broadcast system identifier or "SID" that matches an identifier of a preferred system stored in memory of the station. The second mode allows the user at least one option, which involves selection of a less than preferred system, but with this mode, the mobile station will still make a first attempt to register with a system having a SID matching one stored in memory of the station. A preferred implementation offers the user four system selection options. Options based on stored identifiers include an option to select only the home system, and an option to select from a preferred roaming list (PRL) if the home system is unavailable. In the other two options, if the scanning operations for the home system and systems on the PRL are ineffective, one option involves scanning a band corresponding to that used by the home system. In contrast, the other option involves scanning a band other than that used by the home system. The System Select programming, however, limits the operation in the last optional setting, for example to a set time period or until completion of one call. The preferred embodiment facilitates a substantially one-rate service, where the service provider charges the one rate for all calls through the home system, all systems on the PRL list and any system found during a scan of the home-system band.
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