There are several reasons why you wouldn't receive these messages.
If you attempt to get a text or voice message for strong authentication or to reset your password, you might see a message that reads "Account not authorized to call <phone>."
If you see this message, the country code assigned to your phone number is not currently supported. Contact your system administrator for assistance.
Regulations in some countries, including India and China, prevent automated text and/or voice messages from being delivered to their intended recipients.
If you encounter this problem, choose another strong authentication or password reset method.