Oracle is acquiring TimesTen Inc., a privately held supplier of in-memory database software most frequently used in high-performance applications in telecommunications and financial trading.

No price was announced for the acquisition of the profitable, 8-year-old company. Most of its 90 employees will be retained, Andy Mendelsohn, Oracle senior VP for server technologies, said in a conference call Thursday. Oracle expects to complete the acquisition in July.

TimesTen customers include wireless phone service providers, such as Sprint and T-Mobile, that use the TimesTen database within their billing systems to swiftly check customers' account balances as they place calls. That involves calculating how much the first two minutes of the call will cost versus the amount left in the customer's account. Such billing systems check account balances every two minutes during the call, said Jim Groff, CEO of TimesTen. Another TimesTen user is Amdocs Ltd., which builds TimesTen into its billing software for telecommunications companies and Internet service providers.

Mendelsohn said Oracle and TimesTen databases were complementary products used for different applications. TimesTen uses data delivered at high speed from a computer system's RAM. It's referred to as a real-time system because of the speed at which it can operate, and it's usually closely linked to the operations of a particular application. Time-sensitive data used by TimesTen can be drawn in advance from a back-end database such as Oracle. Both are relational database systems, Mendelsohn said.

Some call centers use TimesTen to access essential customer data as calls come in, allowing the call-center representative to view recent customer-interaction data on a screen while speaking with the customer, Groff said.

TimesTen has a packaged product, TimesTen Cache, that links the TimesTen system to Oracle's database and synchronizes data changes between the two. The company has not produced links for other databases, Groff said.

About half of TimesTen customers are also Oracle customers, many of them in the telecommunications industry, Mendelsohn said. Other customers include Avaya, Cisco Systems, Ericsson, JP Morgan, Lucent NEC, Nokia, and United Airlines. Altogether TimesTen has 1,500 customers using its system, Groff said.

"Oracle customers have been building caching systems with proprietary code in the middle tier for years," Mendelsohn said.

The TimesTen system runs under Unix from Sun Microsystems, IBM, and Hewlett-Packard, as well as Linux and Windows.

The TimesTen acquisition will be a focus of the Oracle consulting organization with customers seeking to build high-performance systems, Mendelsohn said. TimesTen will work with other database systems, he said, just as Oracle Application Server does. But he stopped short of saying additional products will be produced that enable TimesTen to link to competing database systems. Mendelsohn said that will depend on customer demand.