POST to /api/v2/conversations/calls throws 400 on participant address

Problem

Trying to spin up an outbound call via POST to `/api/v2/conversations/calls` using the Python SDK. The token is fresh. The routing queue actually exists in the org. When the payload hits the endpoint, the server rejects it immediately. A 400 error points straight at the participant address format. I've checked the API docs multiple times. It's matching the expected pattern anyway.

Code

```python from platform_sdk.client import ApiClient, Configuration from platform_sdk.models import CreateConversationRequest

config = Configuration(access_token=token)
api_client = ApiClient(config)

body = CreateConversationRequest(
to_type=“phone_number”,
to_address=“+13125550199”,
from_type=“phone_number”,
from_address=“+18005550100”,
routing={
“queue_id”: “a1b2c3d4-e5f6-7890-abcd-ef1234567890”,
“priority”: 0
}
)

response = api_client.conversations_api.post_conversations_calls(body)

<h2>Error</h2>
The response payload comes back like this:
```json
{
 "code": "badRequest",
 "message": "Malformed participant address: +13125550199",
 "status": 400,
 "traceback": ["..."]
}

Question

The routing object looks fine. I've verified the queue ID in the portal manually. Sometimes the SDK expects the address wrapped in a specific dictionary instead of a flat string. I tried changing `to_address` to `{"address": "+13125550199"}` but that just breaks the Pydantic validation. The Python wrapper doesn't seem flexible about the schema. Is there a hidden formatting rule for the outbound call endpoint? Maybe a missing country code prefix or a different to_type value? The logs show the request leaves the server correctly. The token refresh logic is working fine too. Still stuck on the format.