Radio access technology searching method and apparatus for emergency call in terminal supporting a plurality of communication networks

Abstract

A method and an apparatus for performing a Radio Access Technology (RAT) search for an emergency call in a terminal supported by a plurality of communication networks are provided. The method includes identifying at least one communication network which supports a voice telecommunication among the plurality of communication networks providing support in a communication-limited state in which the communication function of the terminal is limited, and performing the RAT search for the identified at least one communication network.

What is claimed is: 
     
         1 . A method of performing a Radio Access Technology (RAT) search for an emergency call in a terminal supported by a plurality of communication networks, the method comprising:
 identifying at least one communication network which supports a voice telecommunication among the plurality of communication networks which the terminal supports in a communication-limited state in which the communication function of the terminal is limited; and   performing the RAT search for the identified at least one communication network.   
     
     
         2 . The method of  claim 1 , wherein the communication-limited state corresponds to at least one of a Subscriber Identity Module (SIM) card un-mounted state, a Personal Identification Number (PIN) lock state, and a PIN Unlock Key (PUK) lock state. 
     
     
         3 . The method of  claim 2 , further comprising:
 when the communication-limited state corresponds to at least one of the PIN lock state and the PUK lock state, determining whether a most recently used network is a network which supports the voice telecommunication, based on information stored in the SIM card, before identifying the at least one communication network which supports the voice telecommunication; and   when the most recently used network is a network which does not support the voice telecommunication, identifying the at least one communication network which supports the voice telecommunication.   
     
     
         4 . The method of  claim 3 , wherein, when the most recently used network is determined to support the voice telecommunication, the performing of the RAT search for the identified at least one communication network comprises performing the RAT search for the most recently used network. 
     
     
         5 . The method of  claim 1 , wherein the at least one communication network which supports the voice telecommunication comprises a communication network employing a Circuit Switched (CS) scheme. 
     
     
         6 . The method of  claim 1 , wherein the performing of the RAT search is implemented based on priorities assigned to the plurality of communication networks. 
     
     
         7 . The method of  claim 6 , further comprising:
 after performing the RAT search, camping on a cell of a corresponding communication network when the corresponding communication network is discovered among the plurality of communication networks.   
     
     
         8 . A non-transitory computer-readable storage medium storing instructions, that when executed, causes at least one processor to perform the method of  claim 1 . 
     
     
         9 . An apparatus for performing a Radio Access Technology (RAT) search for an emergency call in a terminal supported by a plurality of communication networks, the apparatus comprising:
 a communication unit which supports the plurality of communication networks; and   a controller which identifies at least one communication network which supports a voice telecommunication among the plurality of communication networks which the terminal supports in a communication-limited state in which the communication function of the terminal is limited, and performs the RAT search for the identified at least one communication network.   
     
     
         10 . The apparatus of  claim 9 , wherein the communication-limited state corresponds to at least one of a Subscriber Identity Module (SIM) card un-mounted state, a Personal Identification Number (PIN) lock state, and a PIN Unlock Key (PUK) lock state. 
     
     
         11 . The apparatus of  claim 10 , wherein, when it is determined that the communication-limited state corresponds to at least one of the PIN lock state and the PUK lock state, the controller determines whether a most recently used network is the network which supports the voice telecommunication based on information stored in the SIM card, before identifying the at least one communication network which supports the voice telecommunication, and then identifies the at least one communication network which supports the voice telecommunication when the most recently used network is a network which does not support the voice telecommunication. 
     
     
         12 . The apparatus of  claim 11 , wherein when the most recently used network is determined to support the voice telecommunication, the controller performs an RAT search for the most recently used network. 
     
     
         13 . The apparatus of  claim 9 , wherein the at least one communication network which supports the voice telecommunication comprises a communication network employing a Circuit Switched (CS) scheme. 
     
     
         14 . The apparatus of  claim 9 , wherein the controller performs the RAT search based on priorities assigned to the plurality of communication networks. 
     
     
         15 . The apparatus of  claim 14 , wherein the controller camps on a cell of a corresponding communication network when the corresponding communication network is discovered among the plurality of communication networks. 
     
     
         16 . A method of performing a Radio Access Technology (RAT) search for an emergency call in a terminal supported by a plurality of communication networks, the method comprising:
 receiving an input corresponding to a request to perform an emergency call;   identifying at least one communication network which supports a voice telecommunication among the plurality of communication networks which the terminal supports in a communication-limited state in which the communication function of the terminal is limited; and   performing the RAT search for the identified at least one communication network.