phone) market due to the activation of more than one operator. Before 2006, with the appearance of “Iran cell”, Iran mobile telephone had a complete monopoly but after the entrance of the second operator, the competition was formed in this market and the result was the increase of variety in the service of the products, the improvement of network quality, the attempt to keep the users and attracting more share of the market.Here, Iran cell phone market was simulated during 2001 to 2025 by System Dynamics approach. The current study aimed to make an operational model and determine various scenarios for "Hamrah Aval" based on the existing competition market to 2025. In the current study four key variables, number of users, income, costs and capital were simulated. The overall results of the study showed that by continuing the present trend of Cell phone market in Iran, "Hamrah Aval" company is going to lose 10% of market share by 2025. But the change in this trend is possible via various scenarios as creating new infrastructures and increasing the covered regions or the change in the service price.