An integrated IP (Internet Protocol) network that can handle leased-line, voice, and data traffic, offers great advantages in simplifying the networks of communication carriers and reducing network costs compared with separate servicespecific networks. A key issue of such integrated IP networks will be to design a router that can efficiently handle each type of traffic strictly according to its QoS (Quality of Service). Diffserv (Differentiated Services) is a popular solution to handling multiple QoSs, so most routers tend to support it. In this paper, we propose a new DiffServ queue architecture featuring multiple EF (Expedited Forwarding) queues with traffic shaping functions. Because each EF queue has a traffic shaper, its QoS can be controlled without affecting other EF traffic. For example, when the leased line traffic is assigned to the first EF class and VoIP (Voice over IP) traffic to the second EF class, the VoIP traffic is transferred with high QoS even if the leased line traffic has bursty characteristics. This queue architecture can provide a low-latency, assured bandwidth for both leased-line and VoIP traffic. We evaluated the traffic characteristics of VoIP traffic by simulating this queue architecture using various bandwidths and voice codec types. The results indicate that this queuing mechanism can achieve lower latency and better QoS control than the usual DiffServ queue architecture without traffic shaping. The benefits of traffic shaping are more noticeable with low-bandwidth traffic.