https://arstechnica.com/information-technology/2019/09/in-india-you-dont-need-a-google-phone-to-have-a-google-assistant/

India is an enormous developing market for international companies like Google—who list Hindi as the second most-used Google Assistant language, after English—but many of those potential Indian customers don't have smartphones and may frequently be in areas with little or no data coverage. Today, Google announced a partnership with telco carrier Vodafone Idea that brings the Google Assistant to those users by way of a simple, toll-free dial-in service.

Indian users can now call 000-800-9191-000 and interact with the Google Assistant entirely by voice in either English or Hindi, with other language support planned over time. Most of the standard "Hey Google" functionality is available—you might ask what actress played a particular movie role, who sings a popular song, or where to find a nearby store.