Businesses affected by the terrorist attack on the World Trade Center have been turning to disaster-recovery companies in an effort to get their operations back online. "The first call came in at 9:05 [a.m.] Eastern time," just a few minutes after the first plane struck the north tower of the 110-story World Trade Center on Tuesday, Comdisco spokesman Rich Maganini said on Wednesday. "The calls came in almost one after the other right after that." "By midday, we had 25 disaster declarations. We are currently supporting 35 customers, many of which either had operations in the World Trade Center or in nearby buildings," Maganini said. So far, 30 of those companies -- the "vast majority" in New York but some affected by evacuations in Chicago's Sears Tower and elsewhere -- have begun using 13 Comdisco computing facilities, he said. Disaster-recovery companies such as Comdisco specialise in helping customers prepare for cataclysmic events like floods, fires, earthquakes, wars -- or terrorist attacks. They offer clients basic services such as room to bring backup data and set up operations to more sophisticated and expensive "mirroring" in which remote computers simultaneously run the same operations as a company's primary computers. SunGard, a competitor that is attempting to acquire Comdisco, also has begun working with affected customers, with about 750 employees dealing with consequences of Tuesday's attacks. Fourteen of SunGard's customers have declared a disaster and 68 more are on alert, said Dave Palermo, vice president of marketing. SunGard offers everything from mainframes to offices with PCs and phones. "At about 8:54 [a.m. EDT Tuesday], just minutes after the first plane hit, our crisis team began calling customers in the financial district," Palermo said. "Some people are in our facilities now, and some are trying to make their way out of the city to get there." SunGard has 26 facilities around the country with more than a million square feet of floor space. It has desktop computers ready to go, but through agreements with PC manufacturers the company can quickly have thousands more delivered, Palermo said. "We're nowhere near capacity at this point," he said. Consulting firm EDS also is helping about a dozen companies deal with the attack, including a financial services company whose operations are being moved to New Jersey, said Rebecca Whitener, director of security and privacy services. Financial services company Morgan Stanley, with 3,700 employees working in the south World Trade Center tower, is one company that must deal with Monday's collapse of the buildings. Redundant computer systems -- which kick in when the main systems go down -- worked as planned and no client or trade information was lost, according to a company memo seen by CNET News.com. Morgan Stanley could not be immediately reached for comment. SunGard isn't able to accept new customers affected by the attack, Palermo said, but other companies are offering discounts or free services to those affected by the attack. Cervalis, which houses customers' computing operations in its two data centres, also is offering discounted services, said Zack Margolis, vice president of marketing and business development. "Right now we can offer immediate services to companies that need to re-establish employee and customer communications or other information technology infrastructure," Margolis said. Cervalis is offering free consulting services and a first month free for companies that want to use its data centres, he said. OnTrack Data International, a company that recovers data from damaged hard disks or tapes, is changing its pricing rules for those affected by Tuesday's attacks, said Greg Olson, senior director of data recovery. "It's not going to cost the customer anything to have us take a look at the system," and the company will charge less than the market rate of $1,000 to $1,500 per hard disk for data recovery, he said. "We are certainly here to help as much as we possibly can." OnTrack recovers data from about 25,000 hard disks each year and currently is working on thousands of storage systems recovered from Texas floods earlier this year. Most of the company's work is from hardware or software failure or human error, but about 3 percent comes from natural disasters. Several computer companies, including IBM, Sun Microsystems and Hewlett-Packard, also offer disaster-recovery services. Sun Microsystems, which has many customers in the financial district of New York, primarily offers planning services rather than disaster-recovery services, said Kevin Coyne, director for enterprise services. But the server seller is talking to customers, preparing lists of equipment that needs to be replaced and is contacting partners who handle disaster recovery work, he said. "The main thing now is assessing what the needs are and making sure we can provide equipment," Coyne said. While invaluable following a man-made or natural disaster, recovery services can be very expensive, especially when customers require that computer systems be available without delay after an incident. "Costs can go up dramatically as you move toward higher-availability requirements," Coyne said. But often the price tag can be worth it. "A lot of times, customers are finding that losses of $100,000 or $1 million per hour quickly justify the cost of a replicated site," he said. 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