So what is SS7 and for what reason is it used in our daily lives, even though most of us don't know we are using it? Common Channel Signaling System No. 7 (i.e., SS7 or C7) is a global standard for telecommunications defined by the International Telecommunication Union (ITU) Telecommunication Standardization Sector (ITU-T). The standard defines the procedures and protocol by which network elements in the public switched telephone network (PSTN) exchange information over a digital signaling network to effect wireless (cellular) and wireline call setup, routing and control. The ITU definition of SS7 allows for national variants such as the American National Standards Institute (ANSI) and Bell Communications Research (Telcordia Technologies) standards used in North America and the European Telecommunications Standards Institute (ETSI) standard used in Europe (www.pt.com). So what does this mean in lay terms? Essentially there are two components to all telephone calls. The first component is the actual content of the call be it voice or data. The second component is the information that tell telephone exchanges how to establish connections and route the content of the call to the appropriate destination. This second component is a protocol used in the communication between telephone switches in the public telephone network. This protocol "SS7" uses out of band signaling, thus providing a more efficient network.