1. Media Gateways can be utilized at Stage One in the migration from legacy TDM switching networks to newer IP-based soft-switching networks.  Media Gateways will serve as the intermediary devices between existing TDM equipment and IP-based networks to leverage existing legacy equipment while bringing new features and advanced applications to customers.       2. Trunking Media Gateway  is utilized with a softswitch to interface SIP/MGCP/H.248 signaling to SS7 signaling.  The Trunking Media Gateway also provides access from the softswitch to the PSTN to allow for inter-exchange (long distance) calls.  A Trunking Media Gateway can also serve as a bridging element between a Class 5 switch and co-located softswitch through the use of inter-machine trunking (IMT) and/or PRIs       3. Universal Media Gateway  combines some or all of the functionality of the Access, Trunking, and Reverse Media Gateways       3. The Reverse Media Gateway terminates legacy access equipment such as DLCs .  The softswitch interprets that it is interfacing with an IP device and the DLC interprets that it is interfacing with a Class 5 switch.  Some Reverse Media Gateways will even be capable of terminating  proprietary legacy Class 5 switch line bays.     4. 3GDLC Access Media Gateway  is able to provide traditional services such as DSL and POTS to customers, yet it packetizes the traffic for backhaul to a softswitch.