1. A system for text message service, comprising: a SMS (Short Message Service) system configured to include an SMS transmission component and an SMS reception component, and an IMS (Interactive text Message Service) system configured to sending IMS messages using the SMS system as a communication medium, wherein the IMS system comprises: a message translation unit for constructing a request message-type IMS text message by interposing a multiple choice-type answer menu of a text message, entered by a user, between identifiers and also separating answer options using separators, determining whether a received IMS text message is a request message or a response message by checking a request/response flag of the received IMS text message, and, if it is determined that the received IMS text message is a response message, checking a time stamp of the received IMS text message and searching for a request message having a time stamp identical to the time stamp of the received IMS text message; a message transmission component for storing the IMS text message, constructed by the message translation unit, which will be transmitted via the SMS transmission component; a message reception component for storing the IMS text message which was received by the SMS reception component; an IMS interface for relaying communications of IMS text messages between the message transmission component and the SMS transmission component and between the message reception component and the SMS reception component, and adding IMS parameters, including a time stamp indicative of transmission time and a request/response flag, to a teleservice layer of the SMS protocol for the constructed message and then allowing sending SMS transmission of the constructed message; and a message output component for, if the received IMS text message is a request message, outputting the corresponding text message including the answer menu configured using the identifiers and the separators, and, if the received IMS text message is a response message, outputting the corresponding response message.