This thesis attempts to design more efficient STDMer in ISDN with hybrid switches. The contributions are as follows; 1. This thesis introduces a new approach to the voice load offered to elevate the circuit utility. 2. This thesis suggests a new boundary system "MBDV" to reduce Blocking Probability as far as possible. 3. With the new concepts in 1. and 2., performance analysis techniques are derived on the basis of the selected valid concepts and results many researches approved and/or adopted. 4. Finally, this thesis presents an application example of the models and techniques to a practical system many researches use. In addition, this thesis also suggests the practical use of the performance analysis techniques. The computational results show that the system with the new concepts can elevate the performance, and that the analysis techniques can be used practically.