The one-day sale of dollar-denominated bonds opened on Thursday morning. Global Cloud Xchange plans to use the proceeds to refinance $250 million of debt maturing next year and part fund two cable link projects.

"The offering was for raising $250 million, but after receiving interest worth around $3.2 billion, the company is retaining far more," the person told ET.

RCOM, India's fourth-largest mobile phone operator, has been trying to lower its debt burden which has been weighing on its profitability for years now. Its debt fell to aroundRs 34,000 crore after a recent sale of shares to institutional investors and a preferential warrant issue to promoters totaling Rs 6,100 crore.

The latest bond offering will help RCOM's unit repay its existing debt and replace it with one with a longerterm maturity. If the new bonds were sold at a lower interest rate than those they replace, the issue would help reduce the finance cost of the company.

The person didn't provide the coupon rates of the bonds the company plans to refinance.

Executives at RCOM and Global Cloud Xchange declined comment.

Global Cloud Xchange will use $100 million of the bond proceeds to pay its portion of the cost to build two undersea cable links — from Mumbai to Singapore and one connecting Tokyo and the US, the person said.

The unit, incorporated in 1994, owns five subsea cable systems with a total length of 68,698 kilometres with 46 landing stations across 27 countries. RCOM has been in talks with companies, including Hong Kong's Citic Telecom, to sell Global Cloud Xchange in a bid to pare debt.