Integrating the demands of the market economy from the 19th century onwards, the Ottoman Empire realized the infrastructure works, and established telephone exchanges and networks after the Second Constitutional Era. Providing detailed information on the telephone companies, their users and workers, and the role of telephone in daily life, the collection includes records on two companies that were often granted concessions: Ottoman Istanbul Telephone Limited Company, and Izmir and Vicinity Telephone Turkish Incorporated Company. The collection comprises 453 documents and photographs, complemented by the telephone directories spanning the period between 1914 and 1982 and other printed publications at SALT Research, constituting an extensive database on how telephone usage became widespread in Turkey.