Once you register for NCPR on your existing AIRCEL mobile (by sending START to 1909), you are booked for life to remain so. AIRCEL is not providing an option to subscribers to deregister from NCPR.(1) If you dial 1909 IVRS confirms that you are already registered with us in NCPR with registration No. Dxxxxxxxxxxx (unique number). and if you speak to customer service rep at this number, he/she says your number is not in NCPR. how strange!(2) If you send sms "STATUS" to 1909 you receive the following autoreply sms"Dear Customer, your NCPR REg. No. is Dxxxxxxxxxxx (unique number same as announced in the IVRS above). All promotional Calls and SMS to your Mobile should stop by dd/mm/yy."(3) However, if you send "STOP" to 1909 you receive the following prompt autoreply "Dear Customer, you are presently not registered with us in NCPR, Send START 0 or START 1,2,3,4,5,6,7 at 1909 for Registration or Call 1909 for assistance."Earlier (sometime in Sep/Oct. 2011), if one tried hard and requested the customer rep at 1909 to deregister your number from NCPR, what he actually did was deregistered and registered it again, thereby making you stay in NCPR for another extension of 90 days.Maybe AIRCEL doesn't want its customers to deregister and receive messages from web based services and sees them as a dent into their business model.very bad AIRCEL. !Concerned authorities should instruct such erring telecom companies to rectify.PS: i have 2 aircel numbers at home and both are locked in NCPR ; so no question of an exceptional case.