US LEC, bolstered in part by 400 customers acquired through an acquisition, has climbed past the 21,000 total in customers for a growth rate of better than 40 percent in 2004.

So far this year, the company said it has signed on 4,300 business customers across its 15-state, 100 metropolitan-area network.

US LEC’s acquisition of StarNet, a wholesale Internet services provider, brought in more than 400 customers.