Panasonic KX-NS700 Feature Manual page 499

[Example]
Site
PBX
IP-PT
SIP Signal
Voice Packet
P2P connection between an IP extension and IP trunk within a site
Voice packets are transmitted and received between the IP extension and the IP trunk within a site.
P2P connection between branch offices over a VPN (hub-and-spoke connection)
Site
PBX
Calls between IP telephones in separate branch offices establish a P2P connection, using the hub router at
Site to communicate over a VPN.
When the VPN uses a hub-and-spoke (star) topology, the hub router must be configured to allow U-turn connections.
*1
Internet
SIP server
Router
KX-UT
Series
P2P
Hub router
5.2.3 Peer-to-Peer (P2P) Connection
SIP
Remote Office 1
Router
Remote Office 2
Router
*1
Feature Manual 499