When multiple calls are fired, the first person to answer gets connected and the rest of the calls are dropped. To make sure that the call is answered by a person and not by voice mail, use the confirmKey and confirmSound attributes. The example XML here requires the call recipient to input the digit 5 after answering the call to connect. Plivo requests the confirmSound URL using the POST HTTP method for a valid Play, Speak, or a Wait XML element. To play a message asking the recipient to input a DTMF tone to connect the call, return the second XML example. 
from plivo import plivoxml

response = plivoxml.ResponseElement()
response.add(
    plivoxml.DialElement(
        confirm_key='5', confirm_sound='https://<yourdomain>.com/confirm_sound/').add(
            plivoxml.NumberElement('12025551111')).add(
                plivoxml.NumberElement('12025552222')).add(
                    plivoxml.NumberElement('12025553333')))
print(response.to_string())

# XML to play the message
play_message_response = plivoxml.ResponseElement()
play_message_response.add(
    plivoxml.SpeakElement('Enter the digit 5 to connect the call'))
print(play_message_response.to_string())
Response
<Response>
    <Dial confirmSound="https://<yourdomain>.com/confirm_sound/" confirmKey="5">
        <Number>12025551111</Number>
        <Number>12025552222</Number>
        <Number>12025553333</Number>
    </Dial>
</Response>
Return the following XML to play a message.
<Response>
    <Speak>Enter the digit 5 to connect the call</Speak>
</Response>