BSNL  was incorporated on 15 September 2000 and assumed the business of providing telecom services and network management from the erstwhile Central Government Departments of Telecom Services (DTS) and Telecom Operations (DTO) as of 1 October 2000 on a going-concern basis. It is the largest provider of fixed telephony with more than 49% market share, and is the fourth largest mobile telephony provider in India. BSNL is Indias oldest communication service provider and its history can be traced back to the British era. During the British era, the first telegraph line, was established between Calcutta and Diamond Harbour.