403 Forbidden on outbound call creation via POST /api/v2/conversations/calls

Stumbled on a weird bug today with my outbound call automation script. 403 Forbidden. insufficient_scope.

I am trying to programmatically initiate an outbound call on behalf of a specific agent using the Genesys Cloud Conversations API. My Python script successfully grabs an access token via client_credentials, but the request fails immediately when hitting the endpoint. The token looks valid in Postman, yet the script crashes every time. I suspect the scope configuration is off or the token refresh logic is dropping permissions mid-request.

Here is the payload I am sending:
{
“from”: { “phoneNumber”: “+18005550199” },
“to”: [ { “phoneNumber”: “+525512345678” } ],
“wrapUpCode”: { “id”: “wrapup-abc123” },
“agent”: { “id”: “agent-xyz789” }
}

The script executes requests.post(f"{base_url}/api/v2/conversations/calls", json=payload, headers=headers). The response returns a 403 with insufficient_scope claiming I lack conversation:call:write. I added that scope to the application credentials, but the error persists. The token expiry is set to 3600 seconds, and I am not implementing a refresh callback yet. Maybe the grant type handles it differently? The Authorization header follows the Bearer format exactly. I printed the raw response headers and saw x-genesys-system-id match my region. Still failing on scope validation.

  • Regenerated the client secret and verified the conversation:call:write scope is attached to the OAuth application in the admin console.
  • Switched to authorization_code grant locally to bypass the client credentials limitation, but the 403 response remains identical.

How do I properly structure the scope request for this endpoint? Do I need to attach a specific user token instead of a machine token? Any working Python example for this exact call creation flow would help.