Vodafone Idea is likely to mop up about Rs 20,000 crore from its proposed stake sale in mobile tower firm Indus Tower and monetisation of optical fibre assets, sources said. The country's largest telecom operator plans to use the funds for lowering its debt, which stood at Rs 1,23,660 crore at the end of 2018. "Vodafone Idea has received combined valuation of around Rs 20,000 crore for mobile towers and optical fibre assets that it is planning to sell. Discussions have started around it," an industry source close to the development told PTI.