International Business Machines Corp said on Monday it has agreed to buy business software

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integration services company Sterling Commerce from AT&T Inc for about $1.4 billion in cash.

The deal announced Monday would be IBM Corp.'s largest acquisition since it bought Cognos in 2008. AT&T Inc., then known as SBC Communications, paid $3.9 billion for Sterling in 2000, near the peak of the Internet bubble. The unit, which is based in Dublin, Ohio, has little connection to AT&T's main telecommunications business.

AT&T said it expects to record a one-time gain of about $750 million in the quarter in which the transaction closes. The companies said that more than 18,000 global customers use Sterling Commerce systems and services, and that it enables more than 1 billion business interactions a year for its clients.

Following the close of the acquisition, which is expected in the second half of 2010, the approximately 2,500 Sterling Commerce employees will be integrated into the WebSphere organization within IBM's Software Group.

IBM is based in Armonk, N.Y, while AT&T is based in Dallas.