- ⚠️ `PlivoFrameSerializer` and `TelnyxFrameSerializer` now raise `ValueError` at construction when `auto_hang_up=True` (the default) but required credentials are missing, matching `TwilioFrameSerializer`. Previously they constructed successfully and the hangup failed silently at call-end, leaving phantom billable sessions on the provider. If you relied on the old silent behavior, pass `auto_hang_up=False` explicitly or provide the credentials. The specific fields checked are `call_id`/`auth_id`/`auth_token` for Plivo and `call_control_id`/`api_key` for Telnyx.
