
LANCOM 1722 VoIP – LANCOM 1724 VoIP
Chapter 5: Configuring Voice over IP
83
EN
Call routing procedure on outgoing calls
Internal call between two VoIP terminal devices. On the first pass, only the
star is removed from the number, the source line is deleted. During the
second pass, no other route matches this call but the Call Router finds a
matching entry for a SIP user in the list of registered users and can com-
plete the call.
Internal call from VoIP to ISDN. On the first pass, the star is removed from
the number again, the source line is deleted. During the second pass, no
other route matches this call but the Call Router finds a matching entry for
an ISDN user in the list of registered users and establishes the call via the
ISDN interface configured for this user. The destination number is
replaced by the MSN entered for this user '555 555 1' . The PBX receives
the call to '555 555 1' on its external ISDN bus and again determines that
this is an external MSN and can channel the call to the corresponding
ISDN telephone.
Call routing procedure on incoming calls
The incoming call via the number to the MSNs for the connected ISDN ter-
minal equipment is converted into an internal number by the ISDN map-
ping table and passed on to the Call Router. The Call Router cannot find
a matching entry in the call routing table, but it can find a registered user
with the matching internal number. Since the user is an ISDN user, the Call
User
dials
correct call
route
correct user
mapping,
number in
use
Destination
line
VoIP tele-
phone
*14
*#
VoIP softphone
#: 14
internal
VoIP tele-
phone
*11
*#
ISDN users
#: 11
ISDN
Remote site
dials
Call Router
receives
Assigned via
number in
use
correct call
route
Desti-
nation
line
0 123 555 555 1
555 555 1
ISDN mapping
table
List of local ISDN
users
11
ISDN NT