Ameritech will acquire Applied Data Research.

Ameritech said it will pay $215 million for the Princeton, N.J.-based company’s outstanding shares of stock. The $32-per-share tender offer begins Nov. 20 and extends until Dec. 18, Ameritech spokesman Bill Hensley said. Headquartered in Chicago, Ameritech is the parent of the Bell companies serving Illinois, Indiana, Michigan, Ohio and Wisconsin.