There are several online services that allow users to send free group SMS to different mobile numbers at a time. Group SMS means you can send the same message to multiple persons or multiple mobile numbers at a time. Since sending groups SMS from own mobile charges more, people are depending on free online services to send group messages for free. I’ve made a short list of few websites that allow users to either send free SMS or group SMS to mobile numbers in India.
160by2 : This site allows users to send free SMS to Indian mobile numbers, but the only limitation is that the number of characters you can send in a SMS is 80 (160/2=80).
Smsze.com : Smsze.com allows users to compose messages within 148 characters and then send to friends. They also allow users to select messages from a wide collection and then send it to their friends.
Way2SMS : This is one of the oldest and active online messaging services in India. They allow users to send messages within 140 characters and they ensure real time delivery of your messages.
MyCantos : MyCantos is for those people who want to send free text messages and at the mean time they want to socialize with new people online. This site is a perfect combination of free text messaging with social networking.
Note that all above services are free and you will be able to send free SMS to India, however all of them need users to sign up before sending text messages.