Signaling
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... Voice over IP (VoIP).
Although performing telephony call signaling and transporting the
associated audio media over IP ...
... such as call waiting, freephone numbers, etc., implemented in PSTN
protocols such as Signaling System No. 7 (SS7 [6]) should be offered
...
... SIP network. Most commonly this entails that parameters of a
call like the dialed number should be carried over from SS7 signaling
to SIP requests. Routing ...
... Telephones) effort provides a framework for the
integration of legacy telephony signaling into SIP messages. SIP-T
...
... query) along the SIP signaling path during the session. This mid-
call information does not result in any change in the state ...
... which are referenced in Section 5.
Note that many modes of signaling are used in telephony (SS7 ISUP,
...
... new protocol - it is a set of mechanisms for
interfacing traditional telephone signaling with SIP. The purpose of
SIP-T ...
... Gateways: A telephony gateway provides a point of conversion
between signaling protocols (such as ISUP and SIP) as well as
...
... SIP to the Internet and is responsible for
converting between the types of signaling, as well as
interchanging any associated bearer audio media.
...
... gateway and reuse this SS7
information when signaling to the PSTN at the terminating gateway.
...
... By encapsulating ISUP information in the SIP signaling, a SIP network
can ensure that no SS7 ...
... gateways were
relevant here, any protocol for the transport of signaling
information may be used to achieve this, obviating the need for SIP
...
... ISUP content from the SIP message that it receives
and it reuses this information in signaling sent to the PSTN.
...
... flow depicting the ISUP and SIP signaling for a PSTN-
originated call terminating at a SIP endpoint ...
... ISUP. Thus, an originator must
generate the SIP signaling while performing ISUP encapsulation and
...
... interface. The terminator
generates the ISUP appropriate for signaling to the PSTN from the
incoming SIP message ...
... Support for mid-call signaling ...
... implementing overlap dialing see [11]). Also note that the use of
INFO for signaling mid-call DTMF signals is not recommended (see
RFC2833prop(-> 4734prop | 4733prop) ...
...
SIP-T can be employed as an interdomain signaling mechanism that may
be subject to pre-existing trust ...
... SIP-T introduces some challenges in
so far as it bridges carrier signaling with end-user signaling. Any
...
... bridges carrier signaling with end-user signaling. Any
administrative domain implementing SIP-T ...
... Signaling System No. 7; ISDN User Part Signaling procedures", ITU-T Q.764, September 1997, <http://www.itu.int>. ...
... Camarillo, G., Roach, A., Peterson, J. and L. Ong, "Mapping of ISUP Overlap Signaling to SIP", Work in Progress. ...