Growing its customer base by 55 percent year-over-year, regional telecommunications carrier US LEC Corp. (Nasdaq: CLEC) now serves more than 10,000 medium and large-sized customers in the Southeast and Mid-Atlantic.

US LEC reported that the 12-month timeframe ending this November was the fastest growing period in the company’s five-year history. Data services revenue increased nearly 200 percent year-over-year and is now more than $2 million.

Last month, US LEC reported that it cut its third-quarter net loss to $12.8 million, or 48 cents per diluted share, compared with a net loss of $22.8 million, or 85 cents per diluted share, in the same period last year.

Overall revenue also improved for US LEC, increasing 39 percent to $63.9 million. Last year, revenue for the quarter totaled $46 million.

The Charlotte-based company, which recently picked up 150 customers from Interpath, also reports that over 60 percent of all new US LEC customers are taking at least one data product.

“Activating our 10,000th customer is a huge milestone for US LEC and is the result of consistent growth over the last two years,” Aaron Cowell, president and chief executive officer of US LEC, said in a statement. “We’ve achieved double-digit customer growth rates in the past eight quarters, setting company records in the last two quarters.”

Cowell said surpassing these marks has been a direct result of US LEC’s commitment to growing its customer base by selling multiple products to each customer and retaining satisfied customers through outstanding customer care.

“Coupled with our diligence in controlling costs and a dedicated team of over 900 employees, we have been able to grow steadily and achieve improved bottom-line performance,” added Cowell, who replaced Frank Jules as CEO when he resigned in October after joining the company in January. “As a result, US LEC continues to excel as the leading competitive business carrier in the markets we serve.”

Shares of CLEC are priced around $2, an increase of almost 5 percent, or 10 cents, over the previous day’s close of $1.90. The 52-week range for CLEC is from $1.49 to $6.17.