[SIPForum-discussion] how to mark the same transaction?

[Tomasz Zieleniewski]

Hi Jiang,

In order to understand how to identify and distinguish a transaction
one need to investigate how each SIP request and response is matched
to s SIP transaction.

Request matching contains common and type specific rules.
Both for INVITE and non-INVITE transactions requests match to a
specific transaction if the following request parts match:
- branch parameter in the top Via header
- sent-by value in top Via header
- Request-URI
- From header tag parameter
- Call-ID
- CSeq number

INVITE matches to the transaction if the request method, CSeq method, To
header tag parameter and Via header match.
ACK matches to the transaction if To header tag parameter matches
the one in the response sent by UAS.
For other methods a request matches to the transaction if To header tag
parameter, CSeq method and Via header match.

Response matching is much simpler and contains common rules for
INVITE and non-INVITE transactions. Responses match to a specific
transaction if the following response parts match:
- branch parameter in the top Via header
- CSeq method

Kind regards, Tomasz Zieleniewski


2009/5/22 jiangwen jiang <jiangwen127 at gmail.com>

> Hi, all
>      There is a question puzzle me -- how distinguish a sip transaction,
>      using call-ID, tags, or  SDP? or some other informations in sip
> protocal can do that.
>      Thanks for your reply.
>
> Wen
>
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