Telephone Terminology: What Does It All Mean?

When Alexander Graham Bell invented the telephone, he did more than create an object of amusement. He created a tool that has become the primary means of alerting public safety. In addition to traditional telephony, telephone lines and technology have...


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Also included in wireless considerations were FCC requirements that analog phones use any available means to complete 911 calls. Often known as the “strongest-signal concept,†this mandated that emergency requests from one carrier be handled by another if the alternate vendor could better complete the call. Uninitialized telephones, or telephones lacking active service, were also given consideration. While this was designed to protect consumers who had inadvertently allowed subscriptions to lapse or who had no roaming, it soon became a serious issue for public safety when a cottage industry of hand-me-down and expressly manufactured emergency-only telephones sprung up.

Obviously, a significant amount of work was required to enable enhanced wireless solutions. While carriers were assisted by cost recovery, which let them in some cases recover roll-out costs, municipalities often had to fend for themselves. Notable exceptions to this were funds made available through the Public Safety Foundation of America (PSFA) and by the Enhanced 911 Emergency Communications Act of 2003.

To process and dispatch 911 calls, the majority of PSAPs utilize Computer-Aided Dispatch (CAD). With the advent of Phase 2 requirements, mapping support through Geographic Information Systems (GIS) has become increasingly important. In many cases, telephone systems and CAD have been combined through the use of hybrid Computer-Telephone Integration (CTI) that allows sharing of data between applications. Automatic Call Distributors (ACDs) differentiate between emergency and non-emergency calls, routing 911 requests to the first available operator. Facilities must also be capable of processing Telecommunications Device for the Deaf (TDD) and TTY TeleTYpewriter (TTY) calls from the hearing impaired, although this is not new, and required under the Americans with Disabilities Act (ADA).

The newest challenge to public safety communicators comes from the Internet, in the form of web-based telephony. Voice Over Internet Provider lets consumers use special telephones to place calls over the web. Initially, these services did not universally support 911, and when they did, typically route calls to seven-digit non-emergency numbers. Additionally, modem-supported VoIP telephones do not work during power outages and transmissions are subject to the vulnerabilities of the Internet. Routing and ANI/ALI are also a problem. However, in May 2005, the FCC released its First Report and Order regarding E911 Requirements for IP-Enabled Service Providers that addressed significant issues.


Barry Furey, a Firehouse® contributing editor, is director of the Raleigh-Wake Emergency Communications Center in North Carolina. During his 35-year public-safety career, he has managed 911 centers and served as a volunteer fire officer. In 2002, he chaired the Association of Public-safety Communications Officials (APCO) International conference and was awarded an APCO life membership in 2005 for his work in emergency communications.