WiMAX is an assuring technology for providing wireless last-mile connectivity, because of its wide coverage area, high speed data rates and low deployment cost. MAC and physical layer of WiMAX relate to the IEEE 802.16e standard, which describes 5 dissimilar data delivery service classes that can be employed for satisfying Quality-of-Service (QoS) needs of various applications i.e. video conference, VoIP, Web, FTP, etc. This paper is to analyze a case of deployment of QoS over a cellular WiMAX network.