A one-time tax benefit led to a sharp increase in Hawaiian Telecom’s earnings in the fourth quarter of 2012 and for the full year, the company announced Thursday.

The state’s largest telephone company earned $98.6 million, or $9.21 a share, during the final three months of last year, up from $6.5 million, or 63 cents a share, during the same period in 2011. Full-year earnings were $110 million, or $10.32 a share, up from $26.2 million, or $2.41 a share in 2011.

The 2012 results included a $90.8 million noncash tax benefit, company officials said. After adjusting for the benefit, Hawaiian Telcom earned $7.8 million, or 73 cents a share, in the fourth quarter. Adjusted full-year adjusted earnings were $19.2 million, or $1.80 a share.

Overall revenue slipped to $385 million in 2012 from $395 million in 2011 as growth in video, broadband and business information technology services were more than offset by revenue declines from a continued loss of land lines, the company reported. Hawaiian Telcom had 392,877 land lines at the end of 2012, down 5.7 percent from 416,667 land lines at the end of 2011.

Hawaiian Telcom’s video service, launched in July 2011, generated $1.8 million in revenue in the fourth quarter, up from $200,000 from the same period a year earlier. Full-year revenue from the video service totaled $4.9 million, up from $269,000 in 2011. The company had 9,829 video subscribers at the end of 2012, up from 1,620 at the end of 2011.

The company added 1,800 high-speed Internet customers in the fourth quarter, ending the year with 107,600 subscribers, up 4.2 percent from a year earlier.

"The company’s strategy remains to leverage our broadband network to grow next-generation services like video and high-speed Internet in order to successfully offset industrywide structural declines in legacy services and drive overall organic revenue growth," Hawaiian Telcom President and CEO Eric Yeaman told analysts during a conference call following the earnings release.

The company spent $77.7 million on capital improvements last year, 73 percent of which went toward the expansion of its broadband network and video service, Yeaman said. Hawaiian Telcom plans on spending about $80 million in 2013 to continue the expansion, he said.

Hawaiian Telcom shares closed up 59 cents, or 2.09 percent, at $21.18 Thursday on the Nasdaq Global Market.