LANCOM 1722 VoIP – LANCOM 1724 VoIP
Chapter 5: Configuring Voice over IP
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EN
Configuring the ISDN telephones
Configuring the ISDN terminal equipment is generally limited to entering the
external MSN. As a rule, the MSNs were already entered into the ISDN tele-
phones before, and so no changes should be necessary.
5.2.4
Connecting to an upstream SIP PBX
In this example, a branch office network will be connected to the headquar-
ters network over VPN. In addition to data transfer, the telephone structure in
the branch office is also connected to the central SIP PBX. A LANCOM VoIP
Router is used in the branch office network and a LANCOM VPN router, for
example, could act as the VPN end point at the headquarters. The telephony
subscribers at the headquarters receive internal extensions from the number
range '101' to '199'; for each of the branch offices, a 10-digit block from the
200 range is reserved - in this example, '211' to '219'.
Target
Internal telephony between all locations.
External telephony from the branch office via the SIP PBX at the head-
quarters with backup over ISDN.
Calls from the branch office into the local telephone network via ISDN.
Calls to emergency and special numbers via ISDN.
Internet
ISDN
LANCOM VoIP Router BRANCH
OFFICE
ISDN
ADSL
LAN
VoIP telephone
Internal number '211'
VoIP softphone
Internal number '212'
ISDN
VPN
Internal numbers '101'
to '199'
SIP PBX
HEADQUARTERS
LANCOM
VPN router
ISDN gateway
