The way to make calls from your landline in the country is going to change soon. For this, the Central Government has comes out with new rules. In order to make calls on mobile phones from landlines across the country, it will be mandatory for customers to take initiative zero

source https://news.abplive.com/videos/news/india-now-you-have-to-add-0-before-dialing-from-your-landline-new-rules-applicable-from-jan-1-2021-1397610