This API was created by Zendesk. The Zendesk Voice API endpoint is located at https://developer.zendesk.com/rest_api/docs/voice-api/voice. You can find the Zendesk portal / hompage here. The Zendesk Voice API is not currently available on the RapidAPI marketplace.
Click "Request this API on RapidAPI" to let us know if you would like to access to this API.
Meanwhile, you can check out the top APIs that currently available for developers.