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Dialog identity

A dialog is identified by Call-ID, the From tag, and the To tag, and the initial request has no To tag.

Learn in 5 minutes

  1. Name the three dialog-id components
  2. Tell an early dialog from a confirmed dialog
  3. Increment CSeq for a new request inside the dialog

Visual

Early, then confirmed, then BYE · study drawing · cyphermonkeylabs.com UAPeer INVITE 180 200 ACK BYE 200

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No dialog exists until a response carries a To tag. BYE moves a confirmed dialog to terminated.

Worked example

Find the dialog id Dissect the 180. List the three values that identify the early dialog.

  1. Dissect the 180.
  2. Read Call-ID, From tag, and To tag.
  3. Note that 100 would not have been enough.

Fault

The UAC treats a second 180 with a different To tag as a retransmission of the first.

Same Call-ID and From tag with a different To tag is a different dialog. Forking does this on purpose.

Quiz

The dialog id is


An early dialog begins when


The initial INVITE's To header


BYE uses


At the UAS, the local tag is


The remote target comes from


Ecosystem

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

CRM Screen pop uses data the contact center already has: ANI, DNIS, case id. Those values may arrive in SIP headers or in a CTI event after the call is up. The CRM is not a SIP element.

Glossary · Ecosystem map · Ports · Troubleshooting

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