PHONES are jingling off the walls at the major insurance company rating agencies with calls from policyholders anxious to learn the financial status of their particular insurers."We are just flooded with calls - 100 percent above our usual levels," says Kate Ennis, a spokeswomen for the ratings division of Standard & Poor's Corporation. Americans spend 5 percent of their disposable income on life insurance. They have generally assumed their money, invested in $1.4 trillion in assets, was safe. Now insurance companies find themselves under the microscope following the collapse of a several large insurers. On July 16, New Jersey state took over Mutual Benefit Life, the nation's 18th largest insurer with assets of just under $14 billion. This is the largest insurance failure in history. Moody's Investors Service recently downgraded several major insurance companies. Public concern is leading to some cancellations of pension plan policies. In some cases, pension plan monies are being rerouted to the highest-rated insurers, industry experts say. The insurers, for their part, are looking for ways to develop new insurance products with built-in "safety" features. Most importantly, the new products would help to keep the risk of any possible financial failure distanced from the insurers themselves. The area where such new products are most under development - and where concern is perhaps greatest - involves guaranteed investment contracts. During the past decade GICs have become the backbone of most company-sponsored (401-K) retirement plans. Under a typical GIC plan, the insurer pays a fixed rate of return on the capital invested into the plan - often referred to as a fixed-income fund - by the participating company and its employees. Currently, 60 to 70 percent of all 401-K assets are invested in GICs, with the remainder usually placed in different types of equity funds, says Anita Potter, an expert on GICs with the Life Insurance Marketing and Research Association (LIMRA), a trade/consulting firm in Farmington, Conn. Based on the 40-plus insurance companies that respond to surveys by LIMRA, at least $150 billion is invested in GICs. But a number of companies do not report on their plans, which pushes the total well above $150 billio n. The safety of GICs has come under increasing question recently with the collapse of Executive Life, First Capital, Monarch Life, and Mutual Benefit Life. Thousands of policyholders have been left wondering about the value of their benefits. Preliminary analysis of second-quarter figures suggests that such insurance company failures have fostered a decline in participation rates in GIC programs. Ms. Potter figures participation in GICs was down some 18 percent for the first quarter, ending March 31. For the 23 companies reporting to LIMRA, new GIC contributions totaled $9.4 billion, down from nearly $11 billion for the year-earlier period. There is also a "flight to quality," says Potter, with corporations seeking to route pension money to insurers with the highest ratings by Standard and Poor's, Moody's, and A. M. Best Company. Patrick Boyle, senior vice president in charge of pensions for New York Life Insurance Company, also sees a "flight to quality. New York Life is now running about $500 million ahead of last year in terms of new GIC contributions. Mr. Boyle says that his firm's healthy business is linked to New York Life's high (Triple A) rating. New York Life, says Boyle, has sought to be conservative with its investments - thus avoiding high-risk junk bonds or questionable real estate ventures, the factors now imperiling several insurers. New York Life is also exploring new forms of pension products often called "synthetic GICs." Under such plans, the company would, in effect, serve as a money manager, rather than directly holding the pension monies in its general accounts. Boyle says the insurance industry has an obligation to help individuals better diversify retirement dollars. A fixed-income contract may not offset long-term inflation. Thus, in February, New York Life became the first major insurer to offer a mix of no-load mutual funds for defined-contribution-plan pension programs.