Alachua County Sheriff's Office

Alarm Information Alert

Alarm Systems May Not Work With Digital Subscriber Lines (DSL)

NBFAA's Newsletter - National Newsline April 2000.

DSL Lines and their Effect on the Electronic Systems Industry

At NBFAA's recent meetings at ISC West, the Board addressed the potential impact of the widespread installation of Digital Subscriber Lines (DSL) on the electronic systems industry . DSL is a technology that allows digital information to travel to a user over ordinary copper telephone wires, enabling a user to access the Internet and talk on the phone at the same time. There are several varieties of DSL. Often the conglomerate of DSLs is referred to as xDSL.

Among the varieties of DSL are ADSL, G.Lite (or DSL Lite), HDSL and VDSL. HDSL (high bit-rate Digital Subscriber Line) is primarily used between phone companies and corporate sites, whereas, VDSL (very high Digital Subscriber Line) is still in the developing phases, but promises much faster delivery of data over short distances.

ADSL (Asymmetric Digital Subscriber Line) is the type of DSL that most homeowners and small businesses use. It is referred to as "asymmetric" because the majority of its duplex bandwidth is devoted to downstream direction, or sending data to the user. Only a small portion of the bandwidth is available for uploading, since the user primarily relies on downloading information from the Internet.

Up until recently, most DSL installations have been installed with a dedicated line that is not used for traditional analog phone equipment. In these DSL installations, a standard line has been retained for traditional phone equipment. In the past few weeks, DSL providers have begun installing a service that combines DSL with standard phone service on a single line. In order for an analog device, such as a standard phone line or an alarm system, to operate over a DSL line a signal splitter that is designed for that type of line must be installed for each analog device. G.Lite, also known as DSL Lite, will allow analog devices to operate without a splitter. If a splitter is not installed correctly, the alarm system's ability to communicate will be affected. Splitters can be installed by the phone company, the home owner, by a DSL provider or by an alarm company.When a homeowner or business is trying to determine why their alarm system could not communicate during an emergency situation, and discovers it was caused by the installation of a DSL line, it quickly becomes a question of who is ultimately responsible for the alarm's failure to activate properly--the phone company or the alarm company.

NBFAA has been actively researching the potential impact this may have on the electronic systems industry and is forming a task force to lead the association's efforts in this arena. NBFAA is encouraging dealers to monitor the progress of this technology in their community and to watch National Newsline for more information.