I am using Dolphin Service from more than 2 years now.
The reason for using this was they support BSNL network outside Mumbai. which is very good for remotely located areas.
But the network here in Mumbai is very very bad,
I could not find good network any place in Mumbai.
They should have improved their network by now, but no good has been done yet.
They are very economical with their charges.
Giving the best of the plans compared to others.
But bad network has eaten up the cost benefit.