LAN
WAN
Internet
STUN
STUN
STUN
STUN
Server
Server
SIP
SIP
Server
Server
Fixed IP Address
Fixed IP Address
SIP
SIP
Server
Server
STUN
STUN
Server
SIP
Server
Fixed IP Address
SIP
Server
PBX with
V-SIPGW16 Card
ISP/ITSP
ISP/ITSP
ISP/ITSP
ISP/ITSP
ISP/ITSP
ISP/ITSP
Router
(NAT enabled)
PC
IP-PT
Switching
Hub
Note
• If an ISP/ITSP uses a device such as SBC (Session Border Controller), you may not have to enable
the NAT Traversal feature.
• A STUN Server is supplied by an ISP/ITSP, and not included with the PBX.
6 Programming Manual for Virtual SIP Trunk Card
1.1 Information about IP Telephony Service