Path Header

The Path header is defined in RFC 3327, Session Initiation Protocol (SIP) Extension Header Field for Registering Non-Adjacent Contacts. The Path header enables the accumulation and transfer of a list of proxies between a SIP UA and a REGISTER. Its operation is very similar to the Record-Route header in dialog initiating request. Within the context of support for wildcarded PUIs, the Path header is used to ensure that REGISTER responses containing an wildcard ERE transit the P-CSCF, thus enabling the implicit registration of PBX extensions.