Exotel allows you to make outbound calls to DND numbers which have been "whitelisted". This FAQ explains in detail about how to whitelist a DND number.
Exotel also provides a way for you to check if a number has been whitelisted or not. This can be done using the following API.
Request Method: GET
Request URL: /v1/Accounts/<tenant>/CustomerWhitelist/<number>
<Result> <Status>(Whitelist|Blacklist|Neutral)</Status> <Type>(Customer|Agent|API|<empty>)</Type> <Expiry>(-1|<seconds>)</Expiry> </Result>
REST API Specification
|CODE|| Success - 200
Client-Side Error - 4XX
Server-Side Error - 5XX
Whitelist - The number has been whitelisted. You can make outbound calls to this number!
Blacklist - The number has been blacklisted. The number has explicitly unsubscribed from getting your calls.
Neutral - You cannot make outbound calls to this number.
Customer - The customer had made an inbound call to your ExoPhone and has automatically been whitelisted
Agent - This number belongs to your co-worker (Exotel user). All co-workers numbers are automatically whitelisted
API - You have used the Customer whitelisting API to whitelist this number
Result/Expiry: Contains the number of seconds after which the number will not be in this state (typically whitelist)
-1 - There is no expiry. The number remains in this state forever.