As per the regulations laid down by TRAI (Telecom Regulatory Authority of India), no unsolicited telecom commercial communication is allowed to the mobile subscribers registered with DND. This includes voice calls as well as SMS. The regulations along with amendments are as below:

As opposed to call centres and telemarketing companies, SMS service users generally do not have a professional telecalling setup and it is difficult for them to arrange a data which is DND filtered. To filter a data currently the only option available is NDNC (National Do Not Call Registry) from TRAI but to get the data filtered from the site http://ndncregistry.gov.in, you need to register with them. This again is a difficult process. To counter this, we have built our own DND database where we have the most updated DND nos. We have given you the choice to activate the filter. You can send your campaigns without worrying about any action from TRAI(regulator) or operator. To activate online DND filter, after login, Utilities-->Profile-->Online DND Filter-->On.
To send your routine communication messages which don't require any DND filtration, you can simply deactivate the filter. To deactivate, Utilities-->Profile-->Online DND Filter-->Off. Also there will be no deduction of SMS which are not sent on DND nos.