SCIS is the State Company for Internet Services in Iraq that works as the main Internet Service Provider (ISP). After 2003 war in Iraq, there is extremely high demand for Internet service due to very long period of sanctions enforced on Iraq. However, satisfying such high demand is a challenging task; as the cost, number of subscribers and Quality of Service (QoS) are important factors that need to be compromised. SCIS uses Wi-Fi and WiMAX technologies as a wireless broadband solution for last mile access. This paper presents the modeling and analysis of SCIS WiMAX network to improve the overall network performance. End-to-End QoS Model for system-level simulation is modeled using OPNET modeler. The simulated model is evaluated using essential QoS parameters such as end-to-end packet delay, Jitter (Delay variation), and throughput for two types of delay sensitive traffics which are Voice over Internet Protocol (VoIP) and video streaming. The investigation is done for two channel bandwidth. Namely, 5 MHz and 10 MHz. The results show maximum number of active subscribers can be tolerable by each channel bandwidth.