This would require a reverse DNS to determine the domain, which would then, of
course, identify the operator??™s network. As an alternative, this header would be used in
place of the VIA header (the receiving proxy would simply ignore the VIA header and
use the P-VISITED-NETWORK-ID to determine which networks were transited).
P-VISITED-NETWORK-ID: joesnetwork.com
Privacy This header is used to identify when a subscriber wishes to hide his or her
identity from other networks. This could be the case when a subscriber wishes to maintain
secrecy for certain communications, but of course it can be used for illegitimate
purposes as well.
The header is provided in the specifications for legitimate purposes, allowing subscribers
to provide a different identity in the request-URI than they do in the TO header.
78 Chapter 3
The TO header, of course, is displayed to the calling party, while the request-URI is used
by the network for routing and authentication purposes.
PRIVACY: ID
Priority This header was added for providing emergency calls priority over normal
traffic; however, the implementation of this header is operator specific. Therefore, since
it has not been defined for global usage, it may or may not provide priority service for,
say, emergency calls (such as 911 calls in the U.S.).
Other work is being done to define a mechanism for preemption and emergency priority
services in the event of a catastrophe that are not defined here (this is still a work
in progress), but this header is explained so that operators can provide an on-net-type
service if they wish.
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