Why are firewalls and NAT a problem for IP telephony?

Voice communication utilizes a transport protocol optimized for real-time traffic. Firewalls are often configured not to allow this type of traffic. The reason is that such traffic opens up dynamic ports on the firewall making the network more vulnerable to attacks, and accordingly is considered more insecure than e.g. Web traffic which only depends on a fixed port. Another problem occurs when somebody on the outside initiates the voice communication. When using NAT, all computers on the network appears as one (with the same address) from the outside hence making routing difficult.
 

How do I know if I am located behind a firewall?

One way to check if you are behind a firewall is to configure your web radio to use UDP and not http. If this does not work, you are probably located behind a firewall.
 

How do I know if I'm located behind a NAT device?

When you are located behind a NAT device, the NAT server will change your private IP address to a public IP address. If they differ, you are probably located behind NAT. Network Address Translation (NAT) is a technology that enables several machines to share the same IP address. This technology was originally made to help out on the problem caused by too few available unique IPv4 addresses. One positive side effect of this technology is that it also hides the internal structure of an IP network.
When you are located behind NAT your IP address is only valid on your local network. When you are sending traffic to the outside network, a different IP address is inserted in your IP packets instead of your local IP address.

 

What IM clients do you support?

RealTunnel® supports all SIP compliant IM clients and SIP servers. We will continously add more IP telephony clients and applications in our future releases.
 

Will RealTunnel® work in my network?

RealTunnel® is using the existing opening for web traffic in your firewall. As long as you are able to view web pages that are located outside your firewall, RealTunnel® will work in your network. No additional network or security configuration is needed. The traffic from the voice communication software will be transported as normal web traffic until it reaches the RealTunnel® servers on the public Internet. These servers will then forward your traffic to the correct destination.
 

I understand that you are tunneling the traffic as http. Won't this introduce a lot of delay?

A very important issue for voice communication is keeping the total end to end delay as small as possible. To keep it at a minimum, the RealTunnel® solution includes special mechanisms (patented) to ensure that the used web link can support real time, delay sensitive traffic. The best way to check this is to download our client.
 

Paradial provide public access via the RealTunnel® servers. Is it possible to buy the total solution?

Yes, we provide the whole solution, including servers. The whole solution including the servers is offered to companies that either want to use RealTunnel® internally or to provide RealTunnel® and RealSIP® as a service to their users. The system can be setup as a VPN service due to the incorporated SSL functionality with strong encryption keys. Please go to our product pages for further information. You may contact us for more information at info@paradial.com

 

I'm not able to place calls, why?

If your MSN version of RealTunnel® panel just says 'Connected...', then you must sign out of Messenger and then into Messenger again. MSN Messenger doesn't support all call cases due to that NAT traversal support only partially is implemented and due to that MSN overrides its own SOCKS settings which is used to interface the RealTunnel® client. The SIP version of RealTunnel® only says 'Connected' because several registrations are allowed.
 

I don't get connected to your server, why?

If you only get 'Connecting...', the problem might be that we don't manage to read your HTTP proxy settings correctly. If so, enter these manually in the RealTunnel® panel under Options/Preferences/Connection for the MSN Messenger Java version and Options/Preferences/HTTP Proxy for the SIP version and alter correct HTTP proxy settings here. If you are using personal firewall application you must allow the use of RealTunnel®.