Since Quality of Service (QoS) provisioning for multimedia traffic in integrated Wireless and Mobile Networks is becoming an increasingly important objective, in this paper we introduce a novel concept of an adaptive QoS cross-layer framework. The Adaptive QoS framework is proven via novel simulation results in integrated environment with UMTS and IEEE 802.11 networks. The aim of our novel framework is presenting a new module that shall provide the best QoS and lower cost for a given service using one or more wireless technologies in a given time. The analysis of simulation results has shown superior performances with a high level of QoS provisioning in a variety of network conditions. The performance of Adaptive QoS algorithm is evaluated using ns-miracle augmented with our dual-mode Mobile Equipments (MEs) and using statistical analysis.