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An SBC is commonly a B2BUA

RFC 7092 taxonomizes B2BUAs. An SBC is commonly a UAS on one side and a UAC on the other, not a pure proxy.

Learn in 5 minutes

  1. Contrast a B2BUA with a pure proxy
  2. Point at two dialogs in one call
  3. Use RFC 7092 as the taxonomy

Visual

Two Call-IDs for one conversation · study drawing · cyphermonkeylabs.com AliceSBCCarrier INVITE 100 INVITE 200 200

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The inbound side is a UAS dialog. The outbound side is a new UAC dialog.

Worked example

Dissect the outbound INVITE This is the SBC’s outbound INVITE. Which Call-ID belongs to the carrier leg?

    Fault

    The carrier INVITE contains only the SBC Via. The reviewer marks the hop broken.

    The outbound Via is 203.0.113.20 only.

    Quiz

    RFC 7092 is


    On the caller side an SBC commonly behaves as a


    On the callee side an SBC commonly behaves as a


    A pure proxy typically


    In the synthetic ladder the outbound Call-ID is


    Dialog state on a B2BUA is


    Ecosystem

    Glossary, sister systems, and the integration seam for this room.

    Quality management and recording QM scores interactions. The standardized way an SBC forks a session to a recorder is SIPREC.

    Glossary · Ecosystem map · Ports · Troubleshooting

    Sources and go deeper