Dialog matching
OpenSIPS has to match all the sequential requests to a specific dialog. To perform this task, it usually applies a cookie (DID). This cookie is present in the Record-Route headers for initial requests and the Route headers for sequential requests. Let's take a look at the following example for an INVITE and its corresponding sequential request, BYE:
- Initial request:
INVITE sip:5551212@1.1.1.1:5060 SIP/2.0 Record-Route: <sip:2.2.2.2:5060;lr;did=0db.28e94f74>
- Sequential request:
BYE sip:5551212@2.2.2.2:5060 SIP/2.0 Route: <sip:1.1.1.1:5060;lr; did=0db.28e94f74>
If, for some reason, the client is broken and does not insert the Route headers correctly with cookies, you will have to fall back to a pure SIP dialog matching based on call-id ...
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