POST /api/v2/conversations/calls returns 401 Unauthorized despite valid token

NICE CXone API & Integrations
1

POST /api/v2/conversations/calls returns 401 Unauthorized. I have a valid OAuth token from the .NET SDK. The token works for other read endpoints like /api/v2/users/me. But the outbound call request fails immediately. Here is the payload.

{
 "from": {
 "phoneNumber": "+15550100",
 "type": "phoneNumber"
 },
 "to": [
 {
 "phoneNumber": "+15550199",
 "type": "phoneNumber"
 }
 ],
 "route": {
 "type": "user",
 "id": "12345678-1234-1234-1234-123456789012"
 }
}
  • Using Genesys Cloud .NET SDK v4.0
  • Token scope includes conversation:write and call:write
  • User ID is correct and active
  • Tested in Postman with same result

Any idea why the token is rejected specifically for this endpoint?