Patent ID: 6516188
Filing Date: 2003-02-04
Classification: H04W

Abstract:
A method for a mobile radio unit to acquire emergency service from one or more candidate mobile radio communication systems, comprising:(a) attempting, at the mobile radio unit, to acquire normal non-emergency service; (b) if said attempt fails in step (a) and a user of said mobile radio unit originates an emergency call then; (i) scanning an emergency scan list containing said one or more candidate mobile radio communication systems in order to acquire emergency service, wherein said emergency scan list differs from a preferred roaming list stored in said mobile radio unit, the scanning including a first scan of any available AMPS A and B channels, and a second scan if a Service Redirection Message is received by said mobile radio unit, whereby the second scan involves scanning identified channels associated with said one or more candidate mobile radio communication systems one channel at a time in an order provided by the Service Redirection Message; and (ii) originating said emergency call in accordance with said acquired emergency service.