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
Dialling (mathematics) Dialling (mathematics) In somewhat archaic applied mathematics, dialling is the mathematics required to create a sundial face to determine solar time based on the position of the sun. Those skilled in the art were referred to as dialists or gnomonists, the latter derived from the word gnomon, which was a device that used a shadow as an indicator. The mathematician William Oughtred published a book, "Easy Method of Mathematical Dialling", around 1600. Samuel Walker (1716–1782) was a Yorkshire mathematician and diallist. In his later years, Thomas Jefferson was known to practice dialling as a mental exercise. Professor of astronomy at