ADT was founded in 1874 as American District Telegraph when 57 separate telegraph companies merged together. As the telephone became the standard form of communication in the late 19th century, ADT looked for new products and services. Among those were the Western Union company. In 1909, the company began to expand into fire and burglar alarm systems.
In the 1960s, ADT went public. In 1964, the company was found to be a monopoly. The company was forced to adopt a nationwide price list which they could not vary from.
In 1977, ADT was acquired by Lord Ashcroft’s Hawley Goodall company. Hawley was rebranded as ADT.
In the early 1990s, ADT surpasses 1 million customers.
In 1997, the company was acquired by Tyco.
In 2011, Tyco split into 3 separate companies, with ADT being one of the three.
In 2016, the company was acquired by Apollo Global Management for $7 billion and merged it with another security company, Protection One.
The company uses an authorized dealer program. Under this program, independent dealers offer security system installations, which are then monitored by ADT. Some ADT Authorized Dealers use similar DSC, Honeywell/Ademco products as installed by ADT, while other dealers utilize GE or ITI products. Regardless of whether a customer purchases ADT monitoring services directly from ADT or through an authorized dealer, a monitoring contract is required.
Today, ADT is the largest security system provider in the US and Canada with nearly 6.5 million subscribers.