This paper presents a two-dimensionality model for performing QoS connection admission control (CAC) function over a heterogeneous, multi-domain network. To cope with multi-domain network, the CAC mechanisms should perform horizontally in many places as well as vertically. The solution offered in this paper provides a depth view on how end to end QoS CAC is provided over the complicated network environments. Further, additional traffic loads for a call agent due to the CAC model is analyzed theoretically, as well as proves the model is scalable. Finally, this paper describes simulation results in order to show that the model can achieve the required differentiated QoS levels, and can be deployed in operators’ networks.