Frequently Asked Questions
238  
In our network the OpenCom 100 dynamically issues the IP addresses by DHCP. 
Can I firmly assign the IP address for our internal server PCs (mail, Web)?
You need a static address assignment for these PCs. Make the appropriate host 
assignment entries in the Configurator (Network: Hosts menu). Create a static DHCP 
entry for each host assignment in the Network: DHCP menu. Activate “Dynamic and 
static address” for the DHCP server. 
Internet
I cannot access our company Web site.
Outside your system, your company Web site is accessed at “www.firm.com”, but in 
the Configurator you have entered “firm.com” as the domain. Your company’s site 
URL thus counts as an internal URL and can only be accessed by entering the direct IP 
address. If required, change the domain setting in the Network: LAN menu.
Why do some Internet services not work even though they can be used when 
dialling in directly via a modem?
Some Internet services require an active connection coming from the Internet. But 
the configured filter rules prevent this. Plus, it is not possible to establish incoming 
Internet connections with the PCs directly owing to the network address translation 
process.
It is possible to redirect incoming connections in the Configurator, menu Network: 
Port Forwarding. You should secure the redirection target (PC or server) with a 
suitable firewall software.
A SIP connection only passes unidirectional voice. What is the reason?
You did not use the OpenCom 100 as internet router or the STUN server of the SIP pro-
vider is unavailable. You need to activate the SIP support at your internet router, such 
as “SIP-ALG” or “Full Cone NAT” functions. You can also use the OpenCom 100 for 
internet access. Correct the STUN setting in the Telephony: Trunks: SIP Provider 
menu.
Is it possible to use Q.SIG-IP connections via an Internet access with dynamic IP 
address?
Q.SIG-IP connections require a fixed IP assignment for technical and security reasons. 
Therefore you need an Internet access with a fixed IP address. It is possible to tunnel a 
Q.SIG-IP connection through a VPN connection. A VPN connection offers the possi-
bility to determine the peer’s IP address with a DynDNS service during connection 
setup. VPN and DynDNS can be realized with external servers or routers.