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Embedded addresses and NAT
SIP and SDP embed IP addresses. NAT rewrites the packet header and leaves those embedded addresses behind.
Learn in 5 minutes
- Find addresses in Via, Contact, and SDP c=
- Explain why a packet-header NAT does not fix those fields
- Treat a private connection address as non-routable from the public peer
Visual
NAT sees the outer header. SIP and SDP also name addresses in the payload.
Worked example
Read a routable c= line Dissect the offer. c= uses the documentation address 203.0.113.10. The fault beside this lab is the private-address case.
- Press Dissect.
- Find c=.
- Compare it with Contact.
Fault
The carrier never sends RTP. The SDP connection line uses a private address, and that address is non-routable.
The address in c= is private and non-routable from 192.0.2.40. NAT rewrote the packet header, not the SDP body.
Quiz
Ecosystem
Glossary, sister systems, and the integration seam for this room.
Workforce management WFM forecasts volume and builds schedules. It consumes contact-center events. It does not parse Via headers. When a forecast is wrong, the SIP symptom is usually queue delay and 480 or carrier congestion, not a broken dialog ID.