E911 behavior with gsrm in a wireless communication device

Abstract

A wireless communications device attempts to originate an emergency E911 call on a first system. If the system sends a global service redirection message (GSRM), including a redirect list, then the device scans alternate systems from the redirect list. if the redirect systems are not available, the device and again attempts to originate the E911 call on the first system. If the origination is not accepted on the first system, then the device scans an E911 list. If the device fails to acquire a system on the E911 list, the device returns to the first system to reattempt origination if the first system has directed the device to 'return if failure'. If origination is not honored on the first system, the device enters an emergency silent redial scan mode and continues attempts at origination until accepted by the first system. After the wireless communication device has completed an E911 call to a Public Safety Answering Point (PSAP), it enters an emergency call back mode and idles on the system network so that it can receive emergency call backs from the PSAP. If the system sends a GSRM message, the device will scan the redirect list sent to the device in the GSRM message. However, if the systems of the redirect list are not available, the device will not scan an E911 list. Instead, the device will return to the redirecting system and ignore the GSRM messages and wait in the emergency call back mode.