Offer/answer pitfalls in RFC 6337

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RFC 3264 is the rule. RFC 6337 is where the same mistakes show up in real exchanges.

Worked example

Find the delayed offer This INVITE has an empty body. Decide where the offer is allowed to appear.

1. Dissect the INVITE.
2. Confirm Content-Length is 0.
3. Name the message that will carry the offer.

Fault

A re-INVITE changes a=sendrecv to a=sendonly but o= still says session version 2890844526. The peer keeps sending media.

RFC 8866 uses sess-version to signal a modified session description.

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.

Programmable communications APIs Twilio’s docs home is API reference, tutorials, and integration for Twilio products. Elastic SIP Trunking is the SIP-shaped product already cited in this lab. This page does not define the word CPaaS from an RFC. Read the vendor page before you copy a diagram that uses that word.

Glossary · Ecosystem map · Ports · Troubleshooting