United Domains : Provides a platform for securing specialized audio extensions.

If the specific name you want is already taken, you may consider: Register your .radio Domain Name - OnlyDomains

INWX : A registrar specializing in a wide range of TLDs, including global and specialized endings. 2. The "Radio Test" for Domain Names

You can purchase these domains through various services such as: OnlyDomains : Offers registration and renewal services.