Using the free Gmail SMS service users can send text messages to mobile phones via Gmail Chat. Responses to the SMSs will appear as replies in Gmail Chat and conversations will be stored in users’ Chat history, like regular chats. This feature was activated for Indian users on October 10 and is accessible for regular Gmail users and those on Google Apps.
In India the free Gmail SMS service is accessible on 8 major mobile service operators: Aircel, Idea, Loop Mobile, MTS, Reliance, Tata DoCoMo, Tata indicom and Vodafone.
Users are primarily given a credit of 50 messages and for every message sent the credit decreases by one and for each message received in response to a text message sent via Gmail Chat, the user’s credit increases by 5, up to a maximum of 50. When the SMS credit goes down to zero, one credit is added after 24 hours. Google has built in the credit limit to avoid misuse of its free SMS service for marketing/spamming.
Users can also ‘buy’ SMS credit, when they have end of them, my sending a text message to their own phone and then by replying to that message.