public RequestPhoneNumberRequest withMessageType(MessageType messageType) {
        this.messageType = messageType.toString();
        return this;
    }
<p>
The type of message. Valid values are TRANSACTIONAL for messages that are critical or time-sensitive and
PROMOTIONAL for messages that aren't critical or time-sensitive.
</p>

@param messageType
       The type of message. Valid values are TRANSACTIONAL for messages that are critical or time-sensitive and
       PROMOTIONAL for messages that aren't critical or time-sensitive.
@return Returns a reference to this object so that method calls can be chained together.
@see MessageType
aws-java-sdk-pinpointsmsvoicev2/src/main/java/com/amazonaws/services/pinpointsmsvoicev2/model/RequestPhoneNumberRequest.java