Q: What is Free Zone powered by Google?
A: Free Zone is a platform where you can access Google mobile services, namely Google Search, Gmail and Google+, without incurring any data charges. Free Zone gives you the freedom to explore the Internet, search for information, exchange emails and connect with others, free of data charges. You incur data charges only once you move out of the Free Zone.
Q: How do I access Free Zone?
A: If you are an Airtel user, you can access Free Zone by going to http://g.co/freezoneTo use Gmail and Google+ free of data charges you need to sign into your Google Account. If you don't have a Google Account, you can create one on the Free Zone home page. You can use the default phone browser and Opera Mini versions - including 4.3 and above for feature phones, and 5.2+ for smartphones.
Q: Do I need a data plan to use Airtel Free Zone?
A: No, you don't need a data plan to use Free Zone. As long as your phone is able to access the Internet, you can use the Free Zone. However, if you wish to use the Internet on your mobile beyond Free Zone, Airtel will offer you a choice of data plans. You will be informed when you move away from Free Zone while you are using mobile internet.
Q: How does Free Zone benefit me?
A: You can now explore the power of the Internet without incurring any data charges. You can now search and gain access to information whenever you need it, wherever you are. You can exchange emails over Gmail and communicate over work or personal matters as required. And you can share and connect with others on Google+. All this, free of data charges! Even if you have not subscribed to a data plan, you can access the Internet on your mobile, free of data charges, through Free Zone.
Q: Which mobile services can I use free of data charges in Free Zone?
A: You can use Google mobile services i.e. Google Search, Gmail and Google+.
Q: Is there an upper limit to the free usage of Products under Airtel Free Zone?
A: Free Zone is free of data charges for use till you consume less than 1GB of data per month. More than 1 GB of data per month will be charged as per Airtel's data plan on your connection. You will receive notifications as you reach the limit.
Q: How long will I be able to use Free Zone?
A: In case of any changes to the pricing structure in Free Zone, you will be notified by Airtel, well in time.
Q: On which mobile phones can I use Free Zone?
A: Free Zone is available on most internet-enabled mobile phones. If your phone can access the internet, it can access Free Zone.
Q: Which browsers can I use with Free Zone?
A: Free Zone should be accessed with your phone's default browser. Amongst third party browsers Opera Mini can be used to access Free Zone.
Q: Can I use Free Zone on my smartphone or Android device?
A: Yes, you can. However, because Free Zone is designed to be used on all internet-enabled phones, the experience is not optimized for smartphones. Accessing Free Zone via a smartphone on Airtel is free of data charges. However, based on the installed apps and your phone's settings, a smartphone can run a number of background tasks, widgets, or apps (unrelated to Airtel Free Zone) that use data and could incur charges.
Q: Can I use Free Zone on my computer?
A: No, you can only use Free Zone on internet-enabled mobile phones and tablets.
Q: What happens if I click on a link, picture, or attachment?
A: If you click on a link that leads you outside of your Gmail or Google+, you will be charged as per the data plan you have chosen. However, before you enter the chargeable page, you will be notified by Free Zone. If you choose to proceed, Airtel will offer you a choice of data plans, and you can choose your data plan.
Q: What happens when I click on a link in the search results page?
A: When you click on a link in the search results page, you don't pay anything. If you click on a link after this − access to the first page(s) linking from Google Search are free of data charges, for pages thereafter you will need to pay for data usage (but don't worry, before you are charged, you will see a warning page with the option to sign up for a data plan if you want.) So for example, if you click on a search link to a Wikipedia article, you won't pay anything. But if you click on a link within the article, you will be charged for the data costs incurred loading that link. However, before you enter the chargeable page, you will be notified by Free Zone. If you choose to proceed, Airtel will offer you a choice of data plans, and you can choose your data plan.
Q: How many times can I click on a link free of data charges?
A: Every time you click on a link in the search results page it is free of data charges. So if you have clicked through to a link and want to find out more, simply return to your search page and you can click on another link or search again free of data charges. There are no limits on the amount of searches you can make. However there is a Fair Usage Cap of 1 GB per month to avoid misuse.
Q: Who do I contact if I have problems with Free Zone?
A: Please contact Airtel Customer Care by dialing 121 from your phone.
Q: Can I still use Free Zone if I travel to another country?
A: No. Free Zone is offered by Airtel only in India. Once you leave the country you will start roaming, which is not covered by Free Zone.
Q: How do I get help for Google+, Gmail and Search?
A: You can get help at http://support.google.com /mobile
Q: I used Free Zone on my smartphone and I think I got charged for the usage. Why is that?
A: Accessing Free Zone via a smartphone on Airtel is free of data charges. However, based on the installed apps and your phone's settings, a smartphone can run a number of background tasks, widgets, or apps (unrelated to Airtel Free Zone) that use data and could incur charges.
Q: I've tried to use Airtel Free Zone, but it is not working. What could be wrong?
A: While Free Zone can be used on most internet−enabled phones you could run into issues if you are using:
*.A smartphone which does not allow you to change the APN settings
*.A phone that does not support the security certificates we use with Free Zone*
*.A BlackBerry
*.A Google Apps account to login, please create a @ gmail.com account and try again
*.2−factor authentication on your Gmail account
*.A browser with cookies disabled* For example Nokia Series 60 phones prior to the 3rd edition (see http://en.wikipedia.org /wiki/Series_60for more details)

*It works

All you need to know about it is stated above... As for the source, you can google it! Thanks

This post is just too lengthy