A media gateway is an infrastructure network element that converts one or more input protocols or media to one or more output media or protocols, such as TDM circuit-switched networks, ATM or IP. It acts as a translation unit between disparate telecom networks, such as PSTNs, NGNs, second-generation (2G), generation two-and-a-half (2.5G) and 3G RANs, and PBXs. Media gateways support VoIP and/or voice over ATM (VoATM). They manage QoS to ensure that voice traffic has priority and that users receive “toll quality” voice service.