He had been an external examiner for graduate students from universities in Australia, Canada, Hong Kong, India, Singapore, Thailand, and Taiwan.

He was a visiting professor at universities in Australia, India, Japan, Korea, Singapore, and Thailand.

[7] He published in refereed journals and has been a consultant to industry, research institutes, law firms, and academia.

He was invited to be a panelist for the 2011 NSF Graduate Research Fellowship Program (GRFP), with service on the Electrical Engineering Panel.

Rao, along with Nasir Ahmed and T. Natarajan, introduced the discrete cosine transform (DCT) in 1974 which has since become very popular in digital signal processing.