Call Setup at Terminating
Packet Switch (SIP to
ISUP)
This section takes a closer look at the processing and messaging
performed by the TPS when acting as a gateway between an IP
network and the PSTN.
1. An INVITE message arrives at the SIP PH in the SIP GSM. This
message includes:
• IP address of OPS signaling point
• IP address of TPS signaling point
• IP address and port number for the OPS bearer resource
• Encapsulated ISUP IAM message
• A description of the requested session.
2. The SIP PH strips the SCTP and IP headers and compacts the
message to the internal SIP format. The SIP PH then selects a
switching module for the SIP terminal process and forwards the
message to it.
Detailed Call Scenarios - SIP Base
Call Flow
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Lucent Technologies 235-200-118
Issue 3.02B, March 2007