A trunk media gateway (TMG) serves as the bridge between a circuit-based trunk switch and a packet-based IP or ATM backbone network. In certain implementations, it completely bypasses the tandem switch (Class 4). It takes care of the PSTN-to-packet-network transition at the trunk level and is connected to the local or trunk exchange. A TMG has a Class 4 interface and supports VoIP and/or VoATM.