Mumbai and Delhi are on the same time. Both cities use Indian Standard Time (IST, UTC+5:30). When it's 12:00 PM in Mumbai, it's also 12:00 PM in Delhi.
India uses a single time zone across the entire country, so all major cities share the same time.
Any time works! Since both cities share the same time zone, you can call during normal business hours (9:00 AM - 6:00 PM) without any conversion needed.
Mumbai and Delhi are India's two most important cities. Mumbai is the financial capital and entertainment hub (Bollywood), while Delhi is the political capital. The Mumbai-Delhi air corridor is one of the busiest in the world. Flights take about 2 hours.