Got this reply
Dear Customer,
Ref: Email dated 01-11-2011, regarding your concern related to receipt of promotional communication on your airtel mobile number 99XXXXXX.
Thank you for writing to airtel and providing us the opportunity to assist you.
As per the service request number 1031368558, the promotional SMS reported by you sent from an international service provider and does not directly fall under the purview of the NCPR regulations.
However, investigations are on, in consultation with the TRAI, to identify such senders and to evaluate the possible recourse.
We hope that we have been able to address your concern suitably.
Please do write in for any further assistance.
So advertisers are now using international service providers :O