Accepts a phone number and indicates whether the phone holder has opted out of receiving SMS messages from your account. You cannot send SMS messages to a number that is opted out.
To resume sending messages, you can opt in the number by using the OptInPhoneNumber action.
/// Indicates that the user has been denied access to the requested resource.
///
/// Indicates an internal service error.
///
/// Indicates that a request parameter does not comply with the associated constraints.
///
/// Indicates that the rate at which requests have been submitted for this action exceeds
/// the limit for your account.
///
