Fix empty to-tag in SBC on early REFER. #176
Open
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
So you want to send REFER before the dialog has been established? |
|
It establishes an "early dialog" per section 13.2.2.1 or RFC3261. Was previously updated on all replies but was changed in commit 7ba4a52. In the example flow below Bob wants to transfer Alice to Carol, once Carol responds 180 ringing Bob sends the REFER to Alice, Alice responds with 603 because the request is badly formed as it has an empty to-tag. All is fixed by having the SBC update it's tables with the to-tag in the 180 response. I believe there is nothing wrong with this call flow, the only issue is that we haven't taken note of the to-tag so can't include it. Example of REFER without this change... Bob -> SBC (with to-tag) SBC -> Alice (empty to-tag) |
|
Tim writes:
In the example flow below Bob wants to transfer Alice to Carol, once
Carol responds 180 ringing Bob sends the REFER to Alice, Alice
responds with 603 because the request is badly formed as it has an
empty to-tag. All is fixed by having the SBC update it's tables with
the to-tag in the 180 response. I believe there is nothing wrong with
this call flow, the only issue is that we haven't taken note of the
to-tag so can't include it.
I understand that REFER needs to have to tag, but is it OK that Bob
sends REFER when INVITE dialog with Carol is still in early stage?
How is that dialog terminated after REFER?
|
|
Also, Stefan must have had some good reason for commit 7ba4a52. I'm thus afraid that your PR would break some other, much more common use cases. Bob could REFER Alice to Carol without first calling Carol himself or could do the REFER after Carol has answered. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Update to-tag on responses 180 or over rather than 200 to fix empty to-tag on early REFER.