RFC 3263:Session Initiation Protocol (SIP): Locati...
RFC-Ref

host


Click on the red underlined text to get to the source

... URI needs to be resolved in DNS to determine the host that the request needs to be sent to. In some cases, also documented in [1], the request can be sent to a ...
... IP address, port, and transport of the host to which the request is to be sent. ...
... SIP responses to INVITE MUST be sent to the same host. Furthermore, a CANCEL for a particular SIP request MUST be sent to the same SIP ...
... TARGET as the value of the maddr parameter of the URI, if present, otherwise, the host value of the hostport component of the URI. It identifies the domain ...
... UDP, TCP will be used, targeted to a host determined by an SRV lookup of ...


... First Well Known Rule: The first well known rule extracts a key from the AUS. For this application, the first well known rule extracts the host portion of the SIP or SIPS URI. ...



Google
Web
RFC-Ref