20. The ST PH examines the message and forwards it to the ISUP
terminal process. The message is then forwarded to the SIP
terminal process.
21. The SIP terminal process develops a 200 OK (INVITE) message.
A check is made to determine whether encapsulated ISUP is
required. In this example, encapsulated ISUP is not required,
therefore the terminal process discards the ISUP ANM MIME.
This message is in a compact, internal SIP format. The SIP
message is forwarded to the SIP PH in the SIP GSM.
22. The SIP PH receives and accepts the message with no ISUP
MIME and expands the 200 OK (INVITE) message to standard,
external SIP format, adds the appropriate SCTP and IP headers,
and forwards it to OPS via the IP signaling network.
23. The call path through the switch is established and remains
available until the call is terminated.
Call Tear Down at OPS -
No ISUP
This section takes a closer look at the processing and messaging
completed by the OPS when acting as a gateway between the PSTN
and an IP network.
Figure 3-26 Call Tear Down at OPS
Originating Packet Switch (OPS)
Originating
Switch
AM
NLI
PSU
SDL
CCS-SS7
DLTU
SM-2000
TSI
SMP
NLI
Ethernet
SM-2000
SMP
PSU
GQPH
IP Network
SIP-PH
PSUCOM
TSI
OIU
NLI
OC-3c
IP Network
SM-2000
SMP
TSI
OFI-IP
OFI-IP
OC-3c
BRR TP
SIP TP
SONET
PSTN
NLI
DNUS
SM-2000
TSI
SMP
ISUP TP
CM
Terminating
Packet
Switch
(TPS)
CMP
Message
Message
In a standard, external format
In a compact, internal format
1
ISUP REL
2
6
BYE
4
5
OK BYE
7
BYE
9
OK BYE
8
3
SIP without Encapsulated ISUP - Detailed
Call Scenario
Call Flow
....................................................................................................................................................................................................................................
235-200-118
Issue 3.02B, March 2007
Lucent Technologies
3-61
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