A free app for Android, by Product Engg.
Atlas has a huge collection of different modules that you can access for free. From simple courses like reaching out to customers to more complex ones such as new airtel propositions. You can click on those modules and start learning.
The app have plenty of study materials to guide you; pdf files, videos, etc. At the end of a module, you can test your knowledge on what you’ve picked up so far by answering quizzes.
You will also be able to see a breakdown of your performance so you can see how well you are doing.
This app is free and you can download it on your android device.