LANCOM 1722 VoIP – LANCOM 1723 VoIP – LANCOM 1724 VoIP – LANCOM 1823 VoIP
Chapter 1: Introduction
13
EN
you of the version you need. These devices cannot be altered or upgraded to
a system other than that for which it is equipped.
There are even ADSL-over-ISDN connections which are not combined with an
ISDN connection, but with a standard analog telephone connection instead.
In Germany, for instance, all T-DSL connections from Deutsche Telekom AG are
implemented as ADSL-over-ISDN connections.
1.2
What does VPN offer?
A VPN (
V
irtual
P
rivate
N
etwork) can be used to set up secure data communi-
cations over the Internet.
The following structure results when using the Internet instead of direct con-
nections:
All participants have fixed or dial-up connections to the Internet. Expensive
dedicated lines are no longer needed.
All that is required is the Internet connection of the LAN in the headquar-
ters. Special switching devices or routers for dedicated lines to individual
participants are superfluous.
The subsidiary also has its own connection to the Internet.
The RAS PCs connect to the headquarters LAN via the Internet.
HEADQUARTER
VPN GATEWAY
LAN
SERVER
INTERNET
VPN GATEWAY
BRANCH
LAN
PC
LAPTOP
PC
쐋
Computers using remote access,
e.g. home working
