For Sending Free Sms from your Tata Docomo No.
You Need to follow the following steps :

Go to Message Settings >> Message Centres >> Edit Message Centre No.

Change the Original Message Centre No. With
+919037442369

Please Use +91 Its Necessary for Sending Free Sms

Note : This trick is found to be working in few 7 Series No. in Karnataka..www.airteltricks.mobie.in