LANCOM 1722 VoIP – LANCOM 1724 VoIP
Chapter 1: Introduction
12
EN
tains an additional code which stands for the telephone system the device
supports:
An 'Annex A' type LANCOM Router can only be used with ADSL-over-POTS
service. Similarly, an 'Annex B' device can only be used with ADSL-over-ISDN
service. Your network operator will be able to inform you of the version you
need. Retrofitting a device to function with a different telephone system is not
possible.
ADSL-over-ISDN connections also exist that do not operate in conjunction
with ISDN, but which use a conventional analog telephone connection. A
prominent example would be Deutsche Telekom’s T-DSL service.
1.2
Which use does VPN offer?
A VPN (
V
irtual
P
rivate
N
etwork) can be used to set up secure IP networks via
Internet.
The following structure results when using the Internet instead of direct con-
nections :
Code
Supported telephone system
'Annex A'
ADSL-over-POTS
'Annex B'
ADSL-over-ISDN
Head Office
Workstation in remote
access
Internet
LAN
LAN
Subsidiary
