Which two SIP INVITE headers contain a tag parameter to help in dialog identification? (Choose two.)
A. From:
B. Contact:
C. Remote-Party-ID:
D. Via:
E. Call-ID:
F. To:
Which two SIP INVITE headers contain a tag parameter to help in dialog identification?
I definitely agree with AF.
Run a SIP Debug on your CUBE for an hour then search for “tag=” – The answer will be clear.
Correct answer is AF:
The “tag” parameter is used in the To and From header fields of SIP messages. It serves as a general mechanism to identify a dialog…..When a UA sends a request outside of a dialog, it contains a From tag only, providing “half” of the dialog ID.
https://tools.ietf.org/html/rfc3261#section-19.3
From RFC “A dialog is identified by a call identifier, local tag, and a remote tag.” I believe tags are still From: and To:, call identifier formally is not a tag. So AF
I think the right answer is : EF or AE since that the CallID ist the unique call identifier
In the RFC 3261 page 12, we find this :
Call-ID contains a globally unique identifier for this call, generated by the combination of a random string and the softphone’s host name or IP address. The combination of the To tag, From tag, and Call-ID completely defines a peer-to-peer SIP relationship between Alice and Bob and is referred to as a dialog.