Telephone numbers in India Telephone numbers in India Telephone numbers in India are administered under the "National Numbering Plan of 2003" by the Department of Telecommunications. The numbering plan was last updated in 2015. The International Telecommunication Union has assigned the country calling code "91" to India. Subscriber Trunk Dialling (STD) codes are assigned to each city/town/village, with the larger Metro cities having shorter area codes (STD codes), which are from 2 to 8 digits long. For example, Tier-2 Cities or culturally significant towns in India have STD code with 3 digits. For example, Kanpur and Lucknow were the two cities between which the
Subscriber trunk dialling dialled direct, the term has fallen into disuse. When telephone systems were first introduced, subscribers called a telephone exchange and asked a human operator to connect the call to another subscriber on the same exchange; calls to other exchanges were originally not possible. Later it became possible to dial numbers on the same exchange; calls to other exchanges (trunk calls) were possible, but had to be connected by an operator. When subscribers in one area became able to dial non-local subscribers, the term used for the innovation was subscriber trunk dialling. In the UK, STD started before 5 December 1958