Definition
A do-not-disturb (DND) registry is a national or operator-run list of phone numbers whose owners have chosen not to receive marketing calls or messages. Senders must check, or have their provider check, numbers against it before promotional campaigns.
Registries exist in many countries. Examples include the US National Do Not Call Registry for telemarketing calls and India's DND preference system for commercial communications. In the UAE, a Do Not Call Registry (DNCR) applies to telemarketing under TDRA's rules. Some registries are run by the regulator; others are managed by operators.
Scope differs by country: some cover calls only, some also SMS; some allow category preferences (banking, real estate, travel). Transactional messages such as OTPs and account alerts are usually outside scope, but definitions vary, so check the local rules.
A registry is not a substitute for your own consent records. Even if a number is not on the registry, promotional messages generally still need opt-in where the law or operator requires it, and your own suppression list must still be applied.
In practice, the provider or operator often filters registered numbers automatically for promotional traffic. Ask which registries are applied for each country and how often the data is refreshed.