What does Windows error code 7013 (ERROR_CTX_MODEM_RESPONSE_NO_CARRIER) mean?

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ERROR_CTX_MODEM_RESPONSE_TIMEOUT	ERROR_CTX_MODEM_RESPONSE_NO_DIALTONE

ERROR_CTX_MODEM_RESPONSE_NO_CARRIER

Carrier detect has failed or carrier has been dropped due to disconnect.

Windows assigns decimal 7013 and hexadecimal 0x00001B65 to ERROR_CTX_MODEM_RESPONSE_NO_CARRIER. The decisive subject is carrier establishment or retention during a legacy Remote Desktop callback; the value alone does not reveal which object, server, file, session, or transition failed.

The native Value is 7013 (0x00001B65). Preserve this result immediately after the failing Windows call because later logging, cleanup, LDAP, RPC, or file operations can replace the last-error value.

Where the result appears

• processing carrier establishment or retention during a legacy Remote Desktop callback.
• applying a user or server configuration that enables the relevant legacy feature.
• handling a session transition or device response in the Terminal Services stack.
• diagnosing a wrapper that translates a WTS or connection result into Win32 form.

State boundary to prove

This result applies to carrier establishment or retention during a legacy Remote Desktop callback and does not by itself prove that the entire server, directory, disk, session, or application is unavailable. The state boundary to prove for it is whether the modem detects and retains carrier for the remote callback connection. Use dialed number and call timestamps, modem result codes, and line and carrier-detect status as independent evidence. When evidence for it disagrees, preserve timestamps and investigate the transition instead of selecting the most convenient value.

Likely causes

• the remote side did not answer with a compatible modem.
• line quality caused carrier loss.
• the call was disconnected after negotiation.
• modem standards or speeds are incompatible.

Diagnostic sequence

1. capture error 7013 immediately at the API boundary and record the operation that was attempted.
2. identify the exact owner of carrier establishment or retention during a legacy Remote Desktop callback, including object generation, server, path, session, replica, or client context.
3. collect dialed number and call timestamps before restarting a service or changing configuration.
4. compare modem result codes with the documented or observed precondition.
5. correlate line and carrier-detect status with TerminalServices operational logs, session and user-configuration records, device or modem diagnostics, and the caller’s connection trace.
6. determine whether side effects occurred and verify recovery after changing one responsible condition.

Evidence to collect

• dialed number and call timestamps.
• modem result codes.
• line and carrier-detect status.
• whether carrier was never established or later dropped.

Correlate this result with TerminalServices operational logs, session and user-configuration records, device or modem diagnostics, and the caller’s connection trace. Keep the first detailed status even when a later wrapper translates it to error 7013; the first status often distinguishes transport, authorization, storage, schema, state, and application-integrity causes that share the same final Win32 result.

Handling, retry, and recovery

The recovery objective is to verify the remote endpoint and line, lower negotiation settings when appropriate, and retry only after a test call can sustain carrier.

Retry it only after the recorded condition changes and completion state is known. Idempotent queries may be repeated after recovery, but mutations require a state check first; backoff cannot repair malformed input, corruption, missing structure, or policy rejection.

Telemetry and support fields

• record ctx_modem_response_no_carrier_api for the producing function or management operation.
• record ctx_modem_response_no_carrier_target for the file, log, session, replica, object, or server identity.
• record ctx_modem_response_no_carrier_state_before and ctx_modem_response_no_carrier_requested_transition.
• record ctx_modem_response_no_carrier_first_status for the earliest lower-level diagnostic.

For support escalation involving it, retain decimal 7013, hexadecimal 0x00001B65, the API, UTC time, target identity, and first subsystem-specific status. Include the smallest reproducible request and evidence that distinguishes this condition from nearby codes. In the context of it, several modem-related values describe legacy callback functionality. they should be interpreted in that historical configuration context rather than as a generic modern rdp network failure.

Difference from nearby results

ERROR_CTX_MODEM_RESPONSE_NO_DIALTONE fails before dialing; this code occurs after dialing or negotiation begins

Practical validation scenario

A callback reaches the remote number but carrier drops during negotiation. Testing both modems at a common speed isolates an incompatible configuration. The negative test should preserve the responsible condition and reproduce it; the recovery test should change only the identified cause, repeat the same operation, and verify both success and the absence of an unintended partial side effect.

Developer and administrator guidance

Administrators handling it should first decide whether the legacy callback or redirection feature is still required. Developers should treat connection-state notifications as state transitions and device failures as component-specific results instead of mapping every value to a generic RDP network outage. Code that exposes it through RPC, JSON, REST, PowerShell, or another protocol should preserve the Win32 domain, decimal 7013, hexadecimal 0x00001B65, and original component diagnostic.

References

• Microsoft: Win32 system error range containing this code — official context relevant to it.
• Microsoft: Remote Desktop Services API — official context relevant to it.
• Microsoft: WTS configuration classes — official context relevant to it.
• Microsoft: WTSAPI32 reference — official context relevant to it.

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