A pair of Adtran executives has left the company to lead Digium, an eight-year-old maker of open-source enterprise telephony platforms based in the same town.

Danny Windham, Adtran’s director and chief operating officer, will resign both posts on Feb. 12 to become Digium’s new chief executive officer. Steven Harvey, Adtran’s vice president of enterprise networks and competitive service provider sales, will become Digium’s vice president of worldwide sales.

Windham has been with Adtran since 1994, rising through the ranks of the company’s enterprise networks division to become COO in September 2005. He was elected to the board a year ago last week.

Harvey told Adtran last Friday that he was resigning, effective immediately.

Mark Spencer, who was an Adtran intern before he became Digium’s founder and president, will adopt the newly created role of chief technology officer.

Adtran made an unknown equity investment in Digium starting in 2000. Both companies are headquartered in Huntsville, Ala., and their products are sometimes used together.