Signaling
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... end-to-end media packets take a different path from
the SIP signaling messages.
During the session ...
... In some cases, it may be useful for proxies in the SIP signaling path
to see all the messaging between the endpoints for the duration of
...
... client to the
server.
Ringback: Ringback is the signaling tone produced by the calling
party's application indicating that a called party is being
alerted (ringing).
...
... proxy servers that are responsible for routing requests, and
improve signaling path robustness, by relying on redirection.
Redirection allows servers to push routing information ...
... header field elapsing. However, this is generally
unnecessary since the endpoints involved will take care of signaling
the end of the transaction.
...
... certificate when they populate the
originating URI of signaling (the From header field) with the same
address-of-record ...
... breach) and acquire the user's permission before continuing to
process the signaling. If the user authorizes this certificate, it
SHOULD be added to the keyring alongside any previous value(s) for
...
... Note that the security of SIP signaling itself has no bearing on the
security of protocols used in concert with SIP ...
... end-to-end
independently of any associated SIP signaling. Media encryption is
outside the scope of this document.
...
... media session. Although it trusts the proxy
server of the domain it is contacting to deliver signaling properly,
it may not want the administrators of that domain ...
... encryption of messages provides the best means to preserve the
confidentiality of signaling - it can also guarantee that messages
are not modified by any malicious intermediaries. However, SIP
requests and responses cannot be naively encrypted ...
... layer security encrypts signaling traffic,
guaranteeing message confidentiality and integrity ...
... attacker preying on this architecture would, for example, be
unable to forge a BYE request and insert it into the signaling
stream between Bob and Alice because the attacker ...
... the original. It would certainly be more difficult for the man-in-
the-middle to emulate the voices of the participants than their
signaling (a practice that was used with the Clipper chip-based
secure telephone).
...
... encrypted request properly, which could lead to some avoidable error
signaling. This is especially likely when an encrypted request is
forked.
...