POST /api/v2/conversations/calls 400 Bad Request on agent-assisted outbound

Hey everyone,

Trying to set up a script that lets an agent kick off an outbound call directly from the interface. I’m using the REST Proxy to hit the Conversations API. The goal is simple: initiate a call on behalf of the currently logged-in agent.

Here is the JSON payload I’m sending:

{
 "from": {
 "phoneNumber": "+15551234567",
 "name": "Test Agent"
 },
 "to": {
 "phoneNumber": "+15559876543"
 },
 "wrapUpCode": "completed"
}

The request returns a 400 Bad Request. The error message is vague, just saying “Invalid request body”. I’ve double-checked the phone number formats and they match the E.164 standard used in our tenant. I also tried adding the agentId field explicitly, but that didn’t help either.

I assumed the OAuth token passed via the REST Proxy would automatically bind the call to the agent context. Is there a specific header or field I’m missing for agent-assisted outbound? Or does this endpoint require a different auth scope than the standard conversation:write?

Any pointers would be appreciated. I’m stuck on this one.