Telephone numbers in India operator as well as the service and the company. Telemarketers have been issued 10-digit telephone numbers starting with 140 (140XXXXXXX) by the Department of Telecommunications on TRAI's request. 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.
All-figure dialling changes were planned to the way calls in and out of the London telephone area were to be handled that required exchange codes to be grouped together into sectors and it was not possible to implement these changes without a transition to all-figure dialling. The General Post Office produced a pamphlet "All-Figure Telephone Numbers" in 1965 which summarised the problems. From 1966, UK telephone dialling codes ceased to be represented with letters. In most areas this did not require any changes to the telephone codes or numbers, e.g. the Sevenoaks STD code changed from 0SE2 to its numerical equivalent 0732.