Discrete event simulations include processes that take place at times with possible waiting tails. The purpose of this paper is to demonstrate the advanced capabilities of the Arena Simulation software tool for modeling discrete simulations. It will be explored the process flow development with multiple conditions as well as the ability of graphic and 3D simulation and simulation results. In the theoretical part will be presented general business simulations and analytical modeling, and described the previous research. Also, the problem of natural gas supply is presented, which shows the current state of natural gas supply at the level of the entire Republic of Croatia. This paper deals with a concrete example and in the practical part is presented the simulation of the business process of connecting consumers to the gas network on the example of the company PLIN VTC. Following the description of the simulation models and the presentation of the software tools of the Arena Simulation software, the step-by-step process of submitting the application in the Arena Simulation tool is presented. Based on the simulation and the results obtained, and the incoming costs and the wait tails, suggestions for improving the model were given. It has been emphasized still underrepresented threedimensional modeling that provides many new features of this tool. In addition, the use of the model in practice has been suggested. The model gives managers an insight into where and how to reduce costs and improve the process for both, the organization and the client.