A method and system for performing admission control in a packet-based telecommunication network includes a backbone network coupled between at least two access networks. When a first user on a first access network wants to communicate with a second user located on a different access network, a request is made to a quality server whether network resources are available. The quality server separately monitors both access networks and the backbone network and determines whether network resources are available to satisfy the request. In one embodiment, a two-tier approach is used wherein a coordinator module interacts with an admission control subsystem including a plurality of subsystem modules. Each admission control subsystem module is responsible for monitoring a part of the network, such as, one access network or a backbone network. The coordinator module determines which subsystem modules are associated with the user request and interrogates such subsystem modules as to resource availability.