Importance

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Abstract

Whenever a mobile station originates an emergency call connection towards a Public Safety Answering Point (PSAP), a first mobile switching center (MSC) serving the mobile station assigns a first temporary local directory number (TLDN) to the call connection. The assigned TLDN is also utilized as the calling party number (CgPn). Subsequently, whenever the mobile station roams out of the first MSC coverage area, the data correlating the first TLDN with the Mobile Station Integrated Service Digital Network (MSISDN) number associated with the roaming mobile station are maintained by the first MSC if a timer assigned to the first TLDN has not expired. Alternatively, the first MSC may also communicate with the second MSC newly serving the mobile station to request and receive a second TLDN associated with the second MSC. Whenever the PSAP requests a call back connection in response to a disconnection of the original emergency call connection, the first MSC forwards the received call setup signal using the stored MSISDN or second TLDN as the new Called Party Number (CdPn).

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First Claim