You can use the User element to specify a SIP endpoint (user) to dial.
You can use multiple User elements within a Dial element to simultaneously call multiple SIP endpoint users. The first user to answer is connected to the current call and the rest are hung up.
Tells the API to play DTMF tones when the call is answered. This is useful when dialing a phone number and an extension. Plivo dials the number, and when the automated system picks up, it sends DTMF tones to connect to the extension.
Allowed values: any digits and the w character. Each w character tells the Plivo API to wait 0.5 seconds.
If set to true, sendDigits is executed when the called party is in early media instead of the answer state.
Allowed values: true, false
List of SIP headers to send, separated by commas. For example, head1=val1,head2=val2,head3=val3,...,headN=valN. The SIP headers are always prefixed with X-PH-, and are always present for each HTTP request called by the dialed leg.
Allowed values: Only [A-Z], [a-z] and [0-9] characters are allowed for SIP header names and values to ensure you can encode them in a URL.