The present invention provides a system and method of mediating cell traffic between an asynchronous transmission mode (ATM) network and an adjacent network, each cell in said cell traffic having a set of transmission parameters related to the ATM network and a respective ATM connection for the cell. In an embodiment the method comprises: (i) identifying for the cell an egress queue family by utilizing a first set of parameters from said set of transmission parameters; (ii) associating with the cell one of a predefined number of egress class of service (COS) levels by mapping a second set of parameters from the set of transmission parameters into one of the egress COS levels; (iii) utilizing the egress COS level associated with the cell to select an egress queue member of the egress queue family identified in step (i), the selected egress queue member being associated with the egress COS level associated with the cell in step (ii); and (iv) providing said cell to said identified queue member for forwarding to said another network.