We study the key performance characteristics of a finite-buffer multi-server queuing system denoted as (GI GI n, m), with general inter-arrival and service times distributions. The concept called Marked Markov Processes is employed to analyze such a system. Its mathematical model is constructed, and marks’ transformations are introduced, which are further applied to calculate the performance characteristics of the system using a special simulation algorithm. Numerical study validates the proposed method employing the comparison of the obtained results with well-known results for (M|M|1), (M|GI|1), and (M|M|n, m) models.