Peer-to-Peer SIP (P2PSIP)
P2P SIP is a recent development that follows the general P2P trend on the
Internet.
The end-to-end nature of the Internet (the dumb network) has led to an
amazing growth of various peer-to-peer applications and to the predominance
of P2P traffic on the Internet, estimated in 2004 and 2005 to be between 60 per-
cent and more than 80 percent of all Internet traffic.
In private networks, commercial P2P IP PBX functions have been imple-
mented that allow advanced enterprise desktop phones to work without any
central IP PBX server. See, for example, the references [5] and [6]. Small SIP
P2P networks (such as for communities of interest) may not require any
servers or other service infrastructure in the network. Very large P2P SIP net-
works may use a hierarchical structure for the self-organizing P2P cloud where
the “supernodes” are the equivalent of SIP servers.
Since P2P VoIP networks do not require any VoIP infrastructure, the ever-
increasing costs to buy and to operate complex VoIP networks are eliminated.
There are also other general benefits to P2P that will be discussed in Chapter
- P2P is, thus, a considerable disruption of the VoIP industry.
Caller Preferences
Caller preference allows a user to specify how a call should be handled in the
network (for example, if the call should be queued or forked to several desti-
nations), and what features should be supported, such as media types,
language, and mobility. Additional preferences are also supported (for exam-
ple, prevent people from the office disturbing someone at their residential
number).
Called party preferences include accepting or rejecting calls (from unlisted
numbers), depending on time of day, location of the called party, origin of the
call, and other criteria.
SIP caller preferences and called party capabilities reveal unprecedented
service capabilities under control of either the caller with the consent of the
called party, with or without the involvement by the service provider. Services
can be customized with ease on a dynamic basis, depending on a large set of
criteria such as presence, time of day, caller or called party identity, call
urgency, personal caller preferences, network status, and the content of exter-
nal databases [2]. User preferences are presented in more detail in Chapter 8,
“User Preferences.”
Internet Communications Enabled by SIP 19