Letter No. Date Description Policy No. Hyp. No. No. 93/Tele/TN/5/TES  15/07/2004 Rationalization of STD scheme on Indian Railways. Setting up of Directory Enquiry Services. RB Tele. 14/2004 STD-04 No. 2003/Tele/MWC/1 19/02/2004 Implementation of Rational/Uniform STD Scheme.   STD-03 No.2000/Tele/MWC/I 03/10/2003 Implementation of uniform STD scheme on Indian Railways.        - Principles there-of   STD-02 No. 92/Tele/MW4/Vol-1 03/12/2002 Implementation of scheme on Indian Railways. - STD Codes   STD-01