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What's the difference between this
special phone and
regular voip phones ?
The developer not only applies P2P
technology, but also the SIP technology.
1. Application of the P2P technology.
This phone use the 3rd generation P2P
technology.
First
P2P-generation: Server-client
The first generation of peer-to-peer
file sharing networks had a centralized file list. In
the centralized peer-to-peer model, a user would send a
search to the centralized server of what they were
looking for. The server then sends back a list of peers
that have the data and facilitates the connection and
download.
The first file-sharing programs marked themselves
by inquiries to a server, either the data to the
download held ready or in appropriate different
Peers and so-called
Nodes further-obtained, so that one could download
there. Two examples were
Napster (today using a pay system) and
eDonkey2000 in the server version (today, likewise
with
Overnet and
KAD - network decentralized).
Second P2P-Generation:
Decentralization
After Napster encountered legal troubles,
Justin Frankel of Nullsoft set out to create a
network without a central index server, and Gnutella was
the result. Unfortunately, the Gnutella model of all
nodes being equal quickly died from bottlenecks as the
network grew from incoming Napster refugees.
FastTrack solved this problem by having some nodes
be 'more equal than others'.
By electing some higher-capacity nodes to be indexing
nodes, with lower capacity nodes branching off from
them, FastTrack allowed for a network that could scale
to a much larger size. Gnutella quickly adopted this
model, and most current peer-to-peer networks implement
this design, as it allows for large and efficient
networks without central servers.
Also included in the second generation are
distributed hash tables (DHTs), which help solve the
scalability problem by electing various nodes to index
certain hashes (which are used to identify files),
allowing for fast and efficient searching for any
instances of a file on the network. This is not without
drawbacks; perhaps most significantly, DHTs do not
directly support keyword searching (as opposed to
exact-match searching).
The best examples are
Gnutella,
Kazaa or
eMule with
Kademlia, whereby Kazaa has still a central server
for logging in.
eDonkey2000/Overnet,
Gnutella,
FastTrack and
Ares Galaxy have summed up approx. 10.3 million
users (as of April 2006, according to slyck.com). This
number does not necessarily correspond to the actual
number of persons who use these networks; it must be
assumed that some use multiple clients for different
networks.
Third P2P-Generation:
indirect and encrypted
The third generation of peer-to-peer networks are
those that have
anonymity features built in. Examples of anonymous
networks are
ANts P2P,
RShare,
Freenet,
I2P,
GNUnet and
Entropy.
A degree of anonymity is realized by routing traffic
through other users' clients, which have the function of
network
nodes. This makes it harder for someone to identify
who is downloading or who is offering files. Most of
these programs also have strong encryption to resist
traffic sniffing.
The developer applies this
technology to this special netphone.
The fourth
P2P-Generation: Streams over P2P
In development.
2. Application of
the SIP technology.
There are
three types of VoIP. The
first is VoIP using .323 protocol (the technology used
by the common phone cards). It needs a VoIP server
respectively on the calling side and receiving side.
When the server on calling side receives a call, it will
convert the call into an information pack and send the
pack through internet to the server on the receiving
side. The server on the receiving side will then
transfer the call to the local telecom network. This
structure has limited number of phone lines linked to
the servers on both sides. Jamming will occur when users
call at the same time. This is especially true on
holidays when it is quite common to spend 30 minutes or
more to get through.
The second type is SIP (also known as soft switch
technology). It uses caller's computer to process the
caller voice into VoIP with SIP label and then send it
to the destination telecom network gateway directly. For
instance, someone flies to Beijing from San Francisco
virtually and to dial the number on Beijing local
telecom network, so no jamming will occur. At present,
mtctel has adopted this technology.
The third type is P2P technology that is similar to SIP
in voice communication. However, the main characteristic
of P2P technology is its capability to stream large
volume multimedia contents. Voice communication is only
one of its functions. The quality of P2P voice
communication is not as good as SIP sometimes since most
of the telecom exchange gateways are not completely
compatible with P2P protocol.
mtctel
products
mtctel
products are the Internet dialing devices which are
based on P2P/SIP technologies and relating in-house developed chips.
mtctel has successfully
won large numbers of users in North America, Europe, and
China.
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