PDF of this tutorialService providers worldwide rely on the SS7 network. It is the backbone of the modern telecommunications network, enabling service providers to interconnect and offer the advanced voice services customer's demand. The SS7 network provides wireline and wireless call control as well as intelligent network (IN) services such as 8XX and 900 number calling, calling name (CNAM) and calling card verification. SS7 also supports government-mandated services like local and mobile number portability (LNP and MNP).
Since the SS7 network was designed for a closed community, the standards bodies developing it were primarily concerned with high availability and redundancy. This ensured the network's ability to protect itself against system failures.
The Telecom Act of 1996 and the advent of voice and data convergence brought unforeseen threats to the signaling environment. The 1996 Act mandated that the small community of incumbent carriers provide nondiscriminatory access to their SS7 networks on an unbundled basis. Unbundling introduced a host of new providers into the SS7 environment. Similar deregulation is occurring worldwide.
At about the same time, demand for Internet Protocol (IP) telephony services interoperating with the SS7 network began to grow. The proliferation of IP to SS7 gateways that have made this possible, coupled with the added complexity and linked nature of SS7, has brought unprecedented instability to this once closed environment.
To address growing security and reliability concerns, Telcordia developed gateway screening standards (GR-82-CORE). These standards set forth limited provisions for examining and controlling inappropriate and potentially harmful traffic. The Telcordia standards may have been adequate at the time. However, as the market evolves, the carrier's ability to control its network interconnections continues to diminish. A more comprehensive approach must be taken to protect the SS7 network and control intercarrier signaling activity.
