Because of the I/O bottleneck, the conventional disk resident database (DRDB) system becomes more and more unsuitable for the needs of real-time high-performance applications. Providing much better response time and transaction throughput as compared to DRDB’s, the main memory resident database (MMDB) system has been more and more widely used in telecom field. In this paper, after studying the MMDB technology, we propose a modified database structure in Color Ring Back Tone (CRBT) service, using MMDB in CRBT service for the first time. Test results show that the performance of CRBT application has been efficiently improved by using MMDB and the CPU utilization has been decreased, which means the system’s capacity of users has been enlarged.