Operating income at Hawaiian Telcom Inc. declined by 15 percent in March, according to filings with the U.S. Bankruptcy Court.

The local phone company said its operating income totaled $8.3 million for the month, which was down from February's $9.8 million.

The results came on revenues of $34.7 million, which were little changed from the previous month.

Hawaiian Telcom, which filed for bankruptcy protection on Dec. 1, is required to file detailed monthly financial statements with the Bankruptcy Court.

In its latest filing, the company said its cash position increased to $97 million in March from February's $91.7 million.

But the company also recorded a number of non-cash costs and one-time charges that increased the company's net loss for the month to $15 million from February's $8.3 million net loss.

They included $2.4 million in bankruptcy-related costs and $3.9 million in noncash losses from the company's investments in interest rate swaps.

Founded in 1883, Hawaiian Telcom is the state's largest phone company, with 1,400 employees and annual revenues of more than $400 million.

As a result of its bankruptcy filing, Hawaiian Telcom suspended all of its interest payments to its bondholders, who hold about $500 million of the company's debt. The company also received bankruptcy court approval to pay interest payments on a portion of the $500 million in bank debts that it owes.