MTNL Mahanagar Telephone Nigam Ltd Investments/Divestments Announcement 2023 - Debt MAHANAGAR TELEPHONE NIGAM LTD. announced the credit rating letter issued by India Ratings & Research Private Limited for their proposed NCDs of Rs 6,661 Crores backed by the Sovereign Guarantee of Government of India..Find Corporate Announcements for Press Releases, AGM, Insider Trading & SAST, Results and Corporate Action for Mahanagar Telephone Nigam Ltd