The objective of this study was to develop a medical information query system based on Unstructured Supplementary Service Data. Several wireless data transmission modes of Global Systems for Mobile networks are discussed and each mode is analyzed in detail. The framework and configuration of the system is described, and functions of main system modules are illustrated. The medical information query system was implemented and tested to demonstrate practicality and reliability. The practical test shows that the system is convenient, efficient, quick, and secure.