I am using Vodaphone since last 10 years. Vodaphone service is best among all the service providers, specially in kolkata.
I have used reliance, airtell, bsnl but among all network coverage of Vodaphone is far better than all. Although Vodaphone internet services is good but voice services is much better than in comparision with Vodaphone internet services.
In kolkata vodaphone is only player who provide unlimited plan in 3G services and no other service provider.
If one wants to go for minimum plan of internet plus voice services than Vodaphone is the only option with unlimited plan.
Customer care of Vodaphone is also much better in comparision with others. They speak very politely and try to sort out the matter as early as possible