Interworking
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... state machines for these two protocols as a recommendation for
implementers to synchronize protocol events in interworking
architectures.
...
...
In most PSTN interworking situations, SIP message bodies will be
required to carry session information ...
... class) are used in the transmission
of call progress information. PSTN interworking in particular relies
on these messages for control of the media channel and timing of call
...
... response code has been sent). For telephony, establishment of media
in the backwards direction is desirable so that tones and
announcements can be played, especially when interworking with a
network that cannot signal call status out of band (such as a legacy
...
... MF network). In cases where interworking has not been encountered,
use of early media is almost always undesirable since it consumes
...
... ISUP, it MUST set the FCI indicator in the generated IAM so that all
interworking-related bits have the same values as their counterparts
in the encapsulated ...
... ISUP. In most cases, these indicators will state
that no interworking was encountered, unless interworking has been
encountered somewhere else in the call path. If usable encapsulated ...
... state
that no interworking was encountered, unless interworking has been
encountered somewhere else in the call path. If usable encapsulated
...
... gateway, it is
STRONGLY RECOMMENDED that the gateway set the Interworking Indicator
bit of the FCI to 'no interworking' and the ISDN ...
... gateway set the Interworking Indicator
bit of the FCI to 'no interworking' and the ISDN User Part Indicator
...
... services).
Note that when 'interworking encountered' is set in the FCI parameter
of the IAM, this indicates that ISUP ...
... of the IAM, this indicates that ISUP is interworking with a network
which is not capable of providing as many services ...
... configurable option, usable at the discretion of service providers,
that will signal in the FCI that interworking has been encountered
(and that ISUP is not used all the way) when encapsulated ...
... SIP response
---------------- ------------
127 interworking unspecified 500 Server internal error
...
...
If the Backward Call Indicators (BCI) parameter of the ACM indicates
that interworking has been encountered (generally designating that
the ISUP network ...
... the ISUP network sending the ACM is interworking with a less
sophisticated network which cannot report its status via out-of-band
signaling ...
... bidirectional media
stream at this time.
When there is interworking with some legacy networks, it is possible
for an ISUP ...
... terminal has been alerted for
many rings but has not been answered. It may also occur in
interworking cases when the network is playing a status announcement
(such as one indicating that a number is not in service ...
...
A 100 response SHOULD NOT trigger any PSTN interworking messages; it
only serves the purpose of suppressing INVITE retransmissions ...
... method
Interworking indicator: 0 no interworking
End-to-end information indicator: 0 no end-to-end ...
... Note that when the ISUP Backward Call Indicator parameter
Interworking indicator field is set to 'interworking encountered',
this indicates that ISDN ...
... ISUP Backward Call Indicator parameter
Interworking indicator field is set to 'interworking encountered',
this indicates that ISDN is interworking ...
... interworking encountered',
this indicates that ISDN is interworking with a network which is not
capable of providing as many services ...
... encapsulated ISUP will signal in the
BCI that interworking has been encountered, and that ISUP is not used
all the way, for those operators that as a matter of policy would
...
... all the way, for those operators that as a matter of policy would
rather operate in this mode. For more information on the effects of
interworking see Section 7.2.1.1.
...
... (w/o diagnostic)
413 Request Entity too long 127 Interworking (+)
414 Request-URI too long 127 Interworking ...
... Interworking (+)
414 Request-URI too long 127 Interworking (+)
415 Unsupported media type 79 Service ...
... implemented (+)
416 Unsupported URI Scheme 127 Interworking (+)
420 Bad extension 127 Interworking (+)
...
... URI Scheme 127 Interworking (+)
420 Bad extension 127 Interworking (+)
421 Extension Required 127 Interworking (+)
...
... 420 Bad extension 127 Interworking (+)
421 Extension Required 127 Interworking (+)
423 Interval Too Brief 127 Interworking (+)
...
... 421 Extension Required 127 Interworking (+)
423 Interval Too Brief 127 Interworking (+)
480 Temporarily unavailable 18 No user responding
...
... timer expiry
504 Version Not Supported 127 Interworking (+)
513 Message Too Large 127 Interworking (+)
...
... Version Not Supported 127 Interworking (+)
513 Message Too Large 127 Interworking (+)
600 Busy everywhere 17 User busy
...
... timer T11's relevance with respect to SIP interworking,
Q.764 [12] explains its use as: "If in normal operation, a delay in
...
... INVITE request within 20
seconds, SIP interworking inarguably qualifies as such a situation.
If the gateway ...
... Circuit Reservation Acknowledgment (CRA) as part of its interworking
procedures - in the event that an MGC does receive a CRM, a CRA
...
... limited degree to which SIP signaling contributes to the interworking
indicators of the Forward Call Indicators and Backward Call Indicator
parameters incurs no foreseeable risks.
...