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Editorial Team
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Asked: 2026-06-17T23:21:50+00:00

I am developing a sip call tracking application. I have used Tag ID fields

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I am developing a sip call tracking application. I have used Tag ID fields to connect the two call legs
of a call. But some times tag ids will not be same.

What i have done is –

The tag ids are associated to a corresponding Call ID.

Is there any other field i need to consider for identifying legs(dialogues) of a call.

enter image description here
The above one is an exmple for 1 call with tag ids. Different colors used for two legs. And the only similarity i have got a number 3568450037 in tag id’s. 10.10.10.120 is the server ip.

I have to find strong connection between the call legs. Please help me…
And please suggest me some links to solve this issue..

thank u…

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1 Answer

  1. Editorial Team

    The Call-ID, From tag and To tag are all that’s used to identify a dialog. From the SIP RFC chapter on Dialogs. The only trick is matching up local and remote tags, i.e. the To header tag at one end of the call matches the From header tag at the other end of the call and vice-versa.

    A dialog is identified at each UA with a dialog ID, which consists of
    a Call-ID value, a local tag and a remote tag. The dialog ID at each
    UA involved in the dialog is not the same. Specifically, the local
    tag at one UA is identical to the remote tag at the peer UA. The
    tags are opaque tokens that facilitate the generation of unique
    dialog IDs.

    Update:

    Following your edit with the table containing the IP addresses and tags there are two completely separate calls involved which each have their own dialog. I guess that your question was more along the lines of how to match two different dialogs from two separate calls rather than trying to match in-dialog transactions/requests.

    There actually isn’t anything in the SIP headers you can use to match two independent SIP dialogs to know that the calls have been bridged together. I assume you are working with a B2BUA since it’s the only common SIP element that bridges calls. One way to match the dialogs is to look into the SDP carried in the INVITE requests and responses. At the very least you can get the port number each leg is sending and receiving on and match them that way.

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