Interconnection usage charges: taxable once telecommunication service definition amended; not taxable for prior period by law. IUC charged by one telegraph authority to another is not taxable under pre-amendment telephone service rules because it is not provided to a subscriber; Law Ministry and Attorney General concurred. The Finance Bill amends the definition of telecommunication service to include IUC and make such services taxable when the amendment is notified. Until that commencement date, service tax does not apply to IUC and contrary circulars are withdrawn.