What does HRESULT 0x80EE001C (RTC_E_SIP_SSL_TUNNEL_FAILED) mean?

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: Cannot establish SSL tunnel to Http proxy

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RTC_E_SIP_UDP_SIZE_EXCEEDED	RTC_E_SIP_SSL_NEGOTIATION_TIMEOUT

RTC_E_SIP_SSL_TUNNEL_FAILED

Operational meaning: `RTC_E_SIP_SSL_TUNNEL_FAILED`

Diagnosis begins inside resolving a SIP destination and establishing UDP, TCP, TLS, or proxy transport before a transaction can proceed, where the relevant condition for this HRESULT is the RTC stack could not create the HTTPS/CONNECT tunnel required to carry secure SIP through an HTTP proxy.

The numeric form of this result is 0x80EE001C in the RTC interface facility 0xEE; an exception translator handling it should preserve this value before converting it into application-facing call or presence states.

Evidence should show that you capture proxy address, CONNECT target, HTTP status, proxy authentication, and TLS start point; the diagnostic distinction is that proxy tunnel establishment happens before end-to-end SIP TLS negotiation.

Signals worth preserving

Code-specific proof: capture proxy address, CONNECT target, HTTP status, proxy authentication, and TLS start point.
Correlation key: DNS query type and answers.
Protocol or object snapshot: local/remote socket tuple.
Last completed transition: proxy tunnel response.
Expected output: SIP transaction timer and retransmit count.

Recovery and control flow

Recovery from this result should be narrow: fix proxy reachability/authentication or choose an allowed direct route; do not disable TLS; while handling this result, do not let a higher layer simultaneously recreate the same session, registration, listener, or profile.

Example: An enterprise proxy denies the CONNECT request to the SIP TLS port.

Protocol and object state

RTC area	`SIP` transport and reachability
Condition to prove	the RTC stack could not create the HTTPS/CONNECT tunnel required to carry secure `SIP` through an `HTTP` proxy
Objects to correlate	`SIP` URI, proxy/registrar address, DNS results, socket, `HTTP` CONNECT tunnel, transaction timer
Safe corrective direction	fix proxy reachability/authentication or choose an allowed direct route; do not disable `TLS`

Verification workflow

Record it and 0x80EE001C at the first RTC method or event that returns it.
Prove the condition by ensuring the trace can capture proxy address, CONNECT target, HTTP status, proxy authentication, and TLS start point.
Apply one controlled change: fix proxy reachability/authentication or choose an allowed direct route; do not disable TLS; then verify the result return value and resulting RTC state.

Actions that do not address this condition

Do not retry rapidly across every resolved address without preserving the failure phase.
Do not switch transports without checking profile policy and authentication constraints.

Do not confuse it with

`RTC_E_INVALID_PROXY_ADDRESS`	the profile’s proxy address is syntactically invalid or unusable as a SIP next hop
`RTC_E_SIP_TIMEOUT`	the local RTC SIP transaction reached its timer limit without a qualifying final response
`RTC_E_SIP_TCP_FAIL`	RTC failed to establish or maintain the TCP transport needed for the SIP request

Technical references

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