A method of a roaming user equipment, LTE,, the method comprising: receiving a text message from a server; obtaining a first billing information including a charge per unit time from the text message, characterized by further comprising: analyzing a usage pattern of the roaming UE, the usage pattern indicating whether the roaming UE uses more data service or more voice service in a roaming area; selecting, from among a plurality of roaming operators having different billing systems, a roaming operator optimized for at least one communication service provided by the application of the roaming UE, based on the usage pattern; accessing the selected roaming operator for the at least one communication service provided by the application; calculating, based on the first billing information, a second billing information corresponding to a usage charge of the at least one communication service provided by the application while the at least one communication service is provided by the application through the accessed roaming operator; and displaying the first billing information and the second billing information on an execution screen of the application while the at least one communication service is provided by the application, wherein the at least one communication service includes at least one of data communication or voice communication, and wherein the plurality of roaming operators comprises a first roaming operator and a second roaming operator, the first roaming operator configured to charge more for a data service, but less for a voice service than the second roaming operator. receiving a text message from a server; obtaining a first billing information including a charge per unit time from the text message, characterized by further comprising: analyzing a usage pattern of the roaming UE, the usage pattern indicating whether the roaming UE uses more data service or more voice service in a roaming area; selecting, from among a plurality of roaming operators having different billing systems, a roaming operator optimized for at least one communication service provided by the application of the roaming UE, based on the usage pattern; accessing the selected roaming operator for the at least one communication service provided by the application; calculating, based on the first billing information, a second billing information corresponding to a usage charge of the at least one communication service provided by the application while the at least one communication service is provided by the application through the accessed roaming operator; and displaying the first billing information and the second billing information on an execution screen of the application while the at least one communication service is provided by the application, wherein the at least one communication service includes at least one of data communication or voice communication, and wherein the plurality of roaming operators comprises a first roaming operator and a second roaming operator, the first roaming operator configured to charge more for a data service, but less for a voice service than the second roaming operator. analyzing a usage pattern of the roaming UE, the usage pattern indicating whether the roaming UE uses more data service or more voice service in a roaming area; selecting, from among a plurality of roaming operators having different billing systems, a roaming operator optimized for at least one communication service provided by the application of the roaming UE, based on the usage pattern; accessing the selected roaming operator for the at least one communication service provided by the application; calculating, based on the first billing information, a second billing information corresponding to a usage charge of the at least one communication service provided by the application while the at least one communication service is provided by the application through the accessed roaming operator; and displaying the first billing information and the second billing information on an execution screen of the application while the at least one communication service is provided by the application, wherein the at least one communication service includes at least one of data communication or voice communication, and wherein the plurality of roaming operators comprises a first roaming operator and a second roaming operator, the first roaming operator configured to charge more for a data service, but less for a voice service than the second roaming operator.