Amazon.com Help: Make Alexa Calls with Your Voice

Note: Alexa Calling does not support calls to the following types of numbers: Emergency service numbers (for example “911”); Premium-rate numbers (for example “1-900” numbers, or toll numbers) ; Three-digit numbers / abbreviated dial codes (for example “211”) International numbers (numbers outside of the U.S., U.K., Canada, and Mexico); Dial-by-letter numbers (for example “1-800-FLOWERS”)

https://www.amazon.com/gp/help/customer/display.html?nodeId=GEC6XC297YU93LDA