DND is a feature that the Telecom Regulatory Authority of India (TRAI) supports to ensure people do not get bombarded by businesses they do not want to interact with.


Exotel differentiates between calls as transactional and promotional.


Transactional calls are the ones where you get in touch with someone who has a relationship with your business.


Promotional calls are the ones that are made purely for marketing.

You can read more about the 2 kinds of calls here.

At Exotel, we do not support promotional calls.

How do I call my customer whose number is on the DND list?


If a customer has been in touch with you over calls or SMS on your Exophone in the last 2 months, you can call or SMS them via Exotel.


These customers are referred to as “Whitelisted Customers”.


My customer has been in touch with me via my website/app. How do I get in touch with them?


You can use our customer whitelisting APIs to get in touch with these customers. This is how it works:


  1. You use the Customer whitelist API and add your DND customers’ numbers into the Whitelist
  2. An SMS is automatically sent to these numbers asking them their permission for you to contact them.
    1. Example: This is to confirm that you have registered with and have permitted us to call you. If this is not the case, please give a missed call to 09XXXXXXXX. Thank you.
  3. If the person does not want to receive calls from you, they can ‘unsubscribe’ by giving a missed call to the number mentioned in the SMS. If they unsubscribe, you will not be able to call him/her.
  4. Once you have ‘whitelisted’ a DND number, you can make outbound transactional calls to that number


In the process of whitelisting, if more than 3 people choose to unsubscribe and not hear from you, the process of whitelisting changes.


Instead of giving a missed call to unsubscribe, they will need to subscribe to your calling by giving a missed call.


This is done to ensure that this whitelist API is used genuinely and only for transactional calls.
You can read more about customer whitelisting and access the code to do this whitelisting using our APIs here.
With this hack, again thanks to Akash Manohar, you can now enter a mobile/landline number and find out the following:

1. If it is registered on DND Registry or not (What is the DND registry? – Read more on our SMS Guidelines post)

2. Which telecom operator the phone number belongs to (e.g. Airtel, Aircel, TATA, Reliance, Vodafone etc.)

3. Which region (state) does the phone number belong to also (e.g. Karnataka, Tamil Nadu etc.)

Hope it helps.