1. Media Gateway
   1. A translation device or service that converts media streams between disparate telecommunications technologies
2. Telecommunication Technologies
   1. PBX
      1. Private Branch Exchange
   2. VoIP
      1. Voice over IP
   3. PSTN
      1. Public Switched Telephone Networks
      2. SS7 (Signaling System Number 7)
      3. POTS (Plain Old Telephone System)
   4. Next Generation Radio Access Networks
      1. 2G
      2. 2.5G
      3. 3G
      4. 4G
      5. 4G LTE
3. Network (Routed) Protocols
   1. IP
      1. Internet Protocol
   2. ATM
      1. Asynchronous Transfer Mode