Comtrex Corporation, a provider of computer-aided design software solutions and services that is based in Charlotte, is being sold.

Avatech Solutions, which is based in Maryland, announced it was buying Comtrex on Monday. Terms were not disclosed.

Comtrex has offices in Charlotte, Greensboro and in the Raleigh-Durham market. The company was founded in 1983.

Avatech said the acquisition is part of its efforts to expand operations across the Southeast. The firm has offices in 13 states.