May 30 (Bloomberg) -- PT Telekomunikasi Indonesia, the nation’s biggest telephone company, said it agreed to buy 49 percent of PT Infomedia Nusantara from PT Elnusa, increasing its stake in the call-center service provider to 100 percent.

Telkom, as the company is known, signed a conditional sales-and-purchase agreement with Elnusa yesterday, Telkom spokesman Eddy Kurnia said by telephone in Jakarta today. Kurnia declined to disclose the value of the investment in Infomedia, which also runs Telkom’s “Yellow Pages” telephone directory.

State-owned Telkom is seeking to boost revenue from outside its mobile-phone business since rising competition forced companies to reduce charges. Profit at the Bandung, West Java- based company fell 22 percent to 2.5 trillion rupiah ($242 million) last quarter, partly because lower call rates outweighed the growth in mobile-phone subscribers.

The Infomedia acquisition is expected to be completed in August, Kurnia said. Telkom’s unit, PT Telekomunikasi Selular, is Indonesia’s largest mobile-phone operator.

Elnusa’s corporate secretary, Heru Samodra, couldn’t be reached at his office. Elnusa is an oil-drilling services provider.

To contact the reporter on this story: Berni Moestafa in Jakarta at bmoestafa@bloomberg.net

Last Updated: May 30, 2009 00:50 EDT