First of all, take note that you must be a non-resident Indian (NRI) in order to legally invest in Indian bonds. An NRI is one who was born in India but resides in another country. Following are the four options:

1. Many NRIs invest in mutual funds. A mutual fund is a type of bond that allows you to pool your money with that of other investors by purchasing a wide variety of securities. To invest in a mutual fund, NRIs have to either see an agent at a mutual-fund house or see if your bank offers mutual funds for online investing.
2. NRIs can also purchase shares through an Indian company. They do this either by visiting a brokerage firm online or on-site. They can either directly purchase a share in the company or make a portfolio investment (purchasing shares of various companies).
3. NRIs can also purchase government-dated securities, which are bonds whose maturities last beyond one year. NRIs can purchase these securities by submitting applications to banks that have been authorized by the Reserve Bank of India to sell the securities.
4. Lastly, NRIs can purchase bonds through Public Sector Undertakings (PSUs) in India. PSUs are companies that perform public-centered activities, such as energy development and civic engineering. Search for eligible Indian banks to purchase a PSU bond.