It all depends on what you want from "using a map service"? Why do you want "extensive data" - what does that really mean for the app?

This is absolutely key. Do you just want a backdrop for your own data, do you want to run queries on the data itself. Etc. Etc. Whatever you choose should be the best fit for you.

For OSM - if you want more data in the area, then you add more data in that area. Mostly the data is added by people like you and me. Sometimes it's added when there is some good compatible open dataset that can be imported.

If you want to talk to OpenStreetMappers then one of the places to sign up to is the Indian OSM Mailing list.

https://lists.openstreetmap.org/listinfo/talk-in

If you open the link provided, you can see that OSM doesn't even have basic road names. So in any app, that would be a big drawback. thanks for your reply. Whats going on my mind is that I will use Google Maps for some time. Cause this will make easy for users. When we will have enough users, we'll make the switch. Porting all our data to OSM. What do you think about this ?

The only way that I can think of being able to have extensive data is to make a separate scraper or something of the sort to look up a location and receive information of that location via the scraper. Such a method would be hard to configure, however.

As far as I'm aware, there are no out of the box solutions to this problem.

Scrapers generally imply liberating information from hard to read sources. I think you are implying that the scraper would scrape / copy data from other copyrighted digital maps to put into OpenStreetMap.

That would not be allowed to happen with OpenStreetMap - for obvious reasons.

The best way to make it work with OSM is form a community to improve the data.