Federal Communications Commission | Clear Channel Communications | Transmission Control Protocol | File Transfer Protocol | Session Initiation Protocol | User Datagram Protocol | BitTorrent (protocol) | Kyoto Protocol | Internet Protocol | Secure Shell | Post Office Protocol | L-3 Communications | Communications Act 2003 | Rogers Communications | Program and System Information Protocol | communications satellite | Discovery Communications | Simple Network Management Protocol | Charter Communications | Internet Message Access Protocol | Section 230 of the Communications Decency Act | Salem Communications | Network File System (protocol) | MCI Communications | Hypertext Transfer Protocol | communications | Secure Hash Algorithm | Reliance Communications | Nuance Communications | Lightweight Directory Access Protocol |
NSA's STU-III, KY-57 and SCIP are examples of systems that operate over existing voice circuits.