Mr. Lankenau was one of the founding members and a president of Tele-Deaf Inc. (TDI), a company founded to obtain, sell, and repair/recondition TDDs for the deaf community. This series includes TDI board minutes, correspondence (mostly about TDD sales and repair), and printed-out texts of TDD conversations Mr. Lankenau had about TDI business.

The bulk of this series consists of monthly service reports and training materials for CAs (communications assistants). The latter were used to educate CAs on deaf culture and TDD use. Some training material from Michigan’s relay service, which Ohio used as a model for its own system, is included here.