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ERROR_CTX_MODEM_RESPONSE_TIMEOUT
The modem did not respond to the command sent to it. Verify that the modem is properly cabled and powered on.
ERROR_CTX_MODEM_RESPONSE_TIMEOUT is Win32 error 7012 (0x00001B64) and concerns waiting for a modem command response in legacy Remote Desktop callback.
What to verify
Verify whether the modem returns a complete command response before the callback timeout expires. Check command start and timeout timestamps, port state and hardware presence, and serial flow-control settings.
Likely causes
- the modem is powered off or disconnected.
- the serial port or driver is unresponsive.
- flow control prevents the reply.
- the configured timeout is shorter than device initialization.
Troubleshooting steps
- Collect command start and timeout timestamps.
- Record port state and hardware presence.
- Correlate serial flow-control settings with TerminalServices operational logs, session and user-configuration records, device or modem diagnostics, and the caller’s connection trace.
Handling, retry, and recovery
Restore physical and driver communication, reset the modem, and retry with a bounded timeout only after the device responds to diagnostics.
Related errors
ERROR_CTX_MODEM_RESPONSE_ERROR receives a negative response; this code receives no timely response
Example
A callback modem remains connected to a powered-off USB serial adapter. Device diagnostics fail identically, confirming that the problem precedes Terminal Services policy.
References
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