- LANCOM connected to the LAN and WAN, an ISDN TE interface is linked to the ISDN NTBA.
- The Internet connection has been set up by means of a VPN tunnel, as has the network connection between the two locations. All terminal devices can contact one another with the IP addresses used.
- A dialing plan with a unique internal telephone number for each piece of terminal equipment to be connected.
- A SIP provider account.