Get Contact ID created in USD Session

In one of our business scenario, we have to create contact in a USD session and then create case for the same contact. On the case form, the customer case field should be auto filled for the new created customer. I am able to get the Full name, phone number and email of newly created contact in the session but unable to have contact GUID.

Following is the expression that I am using and it is working fine for existing contact but not for contact created in new session.

Is there any idea or help that I can get guid of newly created contact in USD session?

LogicalName=incident
new_cuid=[[cti.callid]]
customerid=EntityReference(contact,[[$Context.contactid]])
customeridname=[[$Context.fullname]]
new_ticketsource=100000000