The main objectives of the Third Gas Directive (2009/73EC) approved by the European Union are: unbundling, creating an independent Transport Service Operator (TSO) and ensuring free access to the market. The separation of gas trading from transportation activities required new market rules and gas balancing. Thereby, the TSO's responsibilities are to maintain network pressures within acceptable bounds and to assure residual balancing whereas shippers must ensure adequate gas supplies. Each party involved in natural gas transport can contribute to maintaining the network in balance. If the pressure in the network grid fluctuates beyond certain bounds, each party is responsible for injecting/extracting gas into/out of the network to restore the pressure and keep the balance. The shippers' role is to balance the system if necessary and to ensure enough capacity booked for the natural gas transport. The booking capacity and the uncertainty in gas demand/supply due to alternative fuels, make it difficult for the shippers to deal with capacity booking management. An agent-based model (ABM) is developed for understanding the mechanisms of booking the network such that the system is in balance yet capacity is available to ensure a safe and reliable operation of the grid. It simulates and different booking strategies of shippers. ABM create a flexible environment for experimentation by transposing actors (from the real life) into agents (in the model). They present a promising modelling approach for socio-technical systems to support decision makers. The natural gas supply and demand is simulated; transactions between the parties are being done as well as the call of BPL, if needed. The simulations are used to investigate (new behavioral) strategies of the shippers regarding the network capacity booking. The paper presents the simulation results and reflects on the different strategies and their associated social costs. ; Infrastructures, Systems and Services ; Technology, Policy and Management