LANCOM 1722 VoIP – LANCOM 1724 VoIP
Chapter 1: Introduction
27
EN
can conduct incoming and outgoing calls over SIP and ISDN just like
SIP users. Again, the outside-line code may be necessary for outgoing
calls.
Dynamic ISDN user registration at point- to-point lines
When connecting downstream PBXs to a point-to-point interface of the
LANCOM VoIP Router, the number of possible ISDN terminal devices is limited
by the length of the extension number. With three-figure extension numbers,
almost 1000 terminal devices can be connected, all of which can be managed
as ISDN users in the LANCOM VoIP Router.
Through an ISDN user entry that only defines the length of the extension
number, all ISDN terminal devices with their respective extension numbers can
can be dynamically generated as ISDN users. For all dynamic ISDN users, the
displayed name or the displayed number are all the same.
1.5.3
Number translation at network transitions
LANCOM VoIP Router switch calls between different telephone networks, e.g.
the ISDN network, various SIP provider networks, and the internal telephone
network. These networks generally have different ranges of numbers or even
completely different conventions for addressing subscribers. Whereas the tra-
ditional land-line network uses numerical characters with country code and
area access codes, the world of SIP allows alphanumerical names along with
domain information.
The transition between these zones must guarantee the correct translation of
"telephone numbers" so that the intended subscriber can be reached. For
example, when a call from the land-line network arrives at a public MSN, the
requested telephone number has to be translated to the ISDN user's internal
number. This act of translation is known as "mapping". Mapping incorporates
not only the
called
number, which represents the destination, but the
calling
number for the source as well.
