Use Custom Variables in Post-Call Webhook

We are a CRM for vehicle repairers. The assistant deals with inbound calls to the repairer. Our ideal flow would look like:

1. Using a custom action, the assistant calls our API at the start of each inbound call, it passes the caller's phone number and retrieve a list of active repairs for that customer, including the repair record UUID, the Year/Make/Model, and the Repair Status, Expected Delivery Date etc - for example : {58f21ea2-d3e4-466a-81c0-ef4de5a42d46, 2010 Mercedes C-Class, In Repair, 2024-06-14}, {6225080d-ca70-46a5-b524-466b8c5780c9, 2023 Audi A4, Estimate Sent, 2024-06-24}

2. The assistant asks the customer which repair they’re calling about eg “Are you calling about the 2010 Mercedes C-Class or the 2023 Audi A4?”

3. The assistant can then answer questions about that repair during the call, eg "Your vehicle is currently in repair and should be ready on the 24 June"

4. We store the UUID for whichever repair the customer selected in a custom variable

We then need to make sure the call transcript is assigned to the correct repair record on our side, and take any actions requested by the caller related to that repair record. To do this, we need to know the UUID of the repair selected by the caller.

Ideally, we would include the UUID in the payload sent to our webhook URL at the end of the call.