Why are my SMS messages not being delivered to some Indian numbers?
Indian numbers that can’t receive SMS messages from Twilio numbers may be registered on India’s Do Not Call registry. You can check if a number is in the registry by clicking on “Check Registration Status” and entering the number (without the country code) on the National Do Not Call Registry website. If, for some reason, that site does not work, here is an alternative site which allows you to lookup your number.
Numbers with a preference of ’0′ are unable to receive SMS messages from Twilio numbers at this time.
To update the DNC settings for an Indian number, please follow the directions on the NDNC India webpage