NEW YORK (Wall Street Journal) -- Bermuda-based ADT Ltd. specialises in keeping people out of other folks' houses. Western Resources Inc. is making a $2.8 billion bet that it can use ADT to get into those houses.

Behind Western Resources' hostile bid last week for ADT, the nation's biggest provider of security systems, is a concept known as bundling, which has caught the eye of phone companies, cable providers and gas and electric utilities.

According to the bundling theory, the more services -- like video on demand, Internet access and home security -- that one company can provide through a single bill, the less likely a customer will be to switch.

Thus, spurred by fears that deregulation will chip away at their customer base, power, phone and cable companies are looking to protect and even expand their markets. The companies eventually hope to offer a wide range of services through a single broad-band width cable.

Even though the technology that will allow a multitude of services on one wire is still a decade away, the rush to consolidate such diverse services under one brand name is beginning. Observers believe this is because the race to wire America's households with broad-band cable will be won by the swiftest.

These days, companies that provide security and alarm systems are the darlings of potential bundlers. The security-system business is fragmented and provides big opportunities for growth through consolidation and attracting new customers. Consumers of security systems are far less likely to switch providers when offered a discount from a home-security competitor, allowing phone and power companies the ability to better retain customers in a deregulated climate.

"One thing is clear,'' says Larry Silverman, a software consultant who assists utilities in developing systems that will provide bundled services to the home. "Once you have a broad band into the home, there is absolutely no economic justification for building a second. Therefore whoever gets there first wins.'' But for Western Resources, a Topeka, Kansas, utility holding company, the bid is risky. Joining security systems with electricity could prove a costly way to reach new customers. Moreover, there's no guarantee Western Resources' bid will prevail. Indeed, some analysts are already speculating that Western Resources' decisive move into the home-security industry could spur other phone and utility companies to speed up their entry.

"Western Resources' moves, particularly the hostile bid for ADT, could be opening the floodgates for others,'' says Richard Siber, an analyst for Andersen Consulting in Boston. "No one wants to wait around while someone else establishes a name in the industry.'' David C. Wittig, Western's president and a former investment banker, said the company launched its security-company-acquisition strategy after conducting focus-group testing nationwide "and finding a very high correlation between energy and home security.'' Mr. Wittig says Western's research showed that if offered a choice, most consumers would choose a name-brand security company over the local power company to supply electricity.

Phone companies, lured by the access to millions of high-end consumers, began dipping their toes into the home-security market about two years ago. That's when Ameritech Corp., a Chicago-based local telephone company, acquired the home-security concern SecurityLink.

Ameritech was followed by MCI Communications Corp., which in May launched MCI One, an integrated system that offers phone service, Internet links and a home-security system that it sells in conjunction with Westinghouse Electric Corp.'s alarm business, which was acquired by Western Resources in December.

But while the phone companies have tested the waters, Western Resources seems to have settled on diving in. With the aid of its financial advisers -- Salomon Brothers, Bear, Stearns & Co. and Chase Securities -- Western has spent $410 million since the fall of last year to buy six security companies.

ADT declined to comment on Western's hostile takeover bid. ADT has said that it will review Western's offer "in due course'' and advised holders to await the board's recommendation. Earlier this year, ADT's friendly $4.49 billion merger with Republic Industries Inc., a holding company with interests in electronic security, was foiled in part by Western's opposition. Western is ADT's biggest shareholder, with 27 percent of the Boca Raton, Florida, company's stock.

A question that remains, however, is whether Western and other utilities can make the transition into other businesses without growing pains. Even today, the notion of utilities branching out unsettles shareholders, who grew fond over the years of calling the industry's last diversification by the unflattering malapropism: di-worsification.

That skittishness extends to officials at Kansas City Power & Light Co., which Western is also attempting to acquire through a hostile bid. During early discussions, KCPL's chief executive, Drue Jennings, balked at Western's wide vision of a utility company involved heavily in areas as diverse as telecommunications and online access. But people familiar with the talks between the companies say that position is tempering.

In the mid-1980s, some power companies expanded into businesses as diverse as airlines and drugstore chains, losing hundreds of millions of dollars in the process. This time, the industry seems to be hewing closer to the fundamentals of a business they understand: home-delivered services that rely on a portal into the home, telecommunications and the quick dispatch of manpower during a crisis.

But industry observers question whether power companies are equipped to compete in the home-security business. For one, many aren't as savvy in marketing as the phone companies. Moreover, they aren't yet equipped to provide the same range of services offered by the telephone companies, which can offer wireless service, pagers and in some cases on-line access.

The wireless service is a particularly strong selling point when joined with security systems, which can be disabled if a burglar cuts off the phone lines.

Through their cellular divisions, the phone companies already are in position to offer an inexpensive wireless backup to the alarm in addition to paging services that notify a home or business owner of the emergency. (MCI says it is already exploring such possibilities through its MCI One.) Mr. Wittig, Western's president, responds that electric utilities like Western Resources "are already in the monitoring business today. The cable TV-guys aren't monitoring. It's a one-way business. Telephone does the same thing. But if we have a problem, we dispatch someone out to the site.''