VPNs (virtual private networks) can be built in several ways and can lake use of different combinations of techniques and protocols. The term we will find frequently associated with VPNs is "tunnelling". Technically speaking, a VPN is a very broad definition, and in this article we will focus on what VPNs are available to the end user on the internet and, especially, how to apply VPNs to internet telephony to internet telephony with SIP and Skype.
Both with SIP and Skype, a VPN is used when we want to increase the safety of our firewall or the security of the voice conversation that travels through the internet. We can sometimes use a VPN to make the connection more stable, and under certain circumstances a VPN can be the only way of allowing SIP device or Skype to get through our firewall and work correctly (such is the case when we experienced interrupted calls, or unacceptable jitter on our internet telephone line).
The Skype program was conceived to adapt automatically to almost any computer and network, and it has a few settings available when things don't work as expected. Those settings include the possibility of using a "tunnel" (VPN), but how that is achieved is left to the user. We will have to rent a VPN service ourselves, and we will have to tell the Skype program that we want to connect through a "proxy" server, using the server address, username and password given to us by the provider of the VPN access.
In the case of a SIP device such as a softphone we have more options for using a VPN, and we will mention the two main ones. The first option is to use the tunnelling service that our own VoIP provider might be offering. The second option, as in the case of Skype, is to hire a separate access to a VPN ourselves. Either way, we will be given a server address, username and password that we will use to identify ourselves when we tell our program or SIP device to connect through a "proxy".
It can appear complicated at first, but take a second glance at this article and you might troubleshoot your internet telephone successfully, instead of thinking about dropping the service and losing the benefits of VoIP.
About this Author
If you need more information or support, I have opened a forum in which I will be available to give you my advice. The forum is Voip Digital Phone Forum.
Much more information on VoIP is available at Voip Phone Planet.
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