public String getRegistrationId() {
        return this.registrationId;
    }
<p>
Use this field to attach your phone number for an external registration process.
</p>

@return Use this field to attach your phone number for an external registration process.
aws-java-sdk-pinpointsmsvoicev2/src/main/java/com/amazonaws/services/pinpointsmsvoicev2/model/RequestPhoneNumberRequest.java