More and more users are turning to Voice over Internet Protocol (VoIP) for calling, as businesses and individuals alike discover the power that VoIP has to save money on long distance charges. But with issues like the PRISM affair still fairly fresh in users' minds, concerns about security and eavesdroppers are also coming into play. That's where VoIP can get some help from another technology called the virtual private network (VPN), and the two together can produce a solution that's safe, secure, and simple to use.

Combining the two technologies is actually somewhat natural. A VoIP transmission, after all, is just a kind of specialized data stream, not much different in essential purpose than a Web site, a video or an e-mail – it’s simply a different kind of data. The VPN kicks in to apply the same kind of data encryption technology that would be applied to any other kind of data, thus allowing the whole thing to proceed smoothly. The VoIP gateway creates the data stream, turning an analog voice signal into a digital signal, and then converts it to a set of IP packets, which can be encrypted just like any other data transmission.

Using a VoIP VPN, meanwhile, has some other benefits over the alternatives. Recent studies indicate that using VoIP with an SSL-based VPN can actually boost call quality by bringing together the data packets in the encryption process. VPN has also been shown to have “no negative influence” when it comes to issues like jitter, latency and packet loss overall. 

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Some studies have even found that using a VPN can result in increased bandwidth—a 10 percent gain by some reports—thanks to the increased throughput gained from small packet sizes and increased overhead. Major overhead gains can be had when using a VPN over other methods like SRTP: Enabling things like authentication, encryption, anti-replay attack, among other features, can result in 85 percent overhead in a g723 with 30ms RTP and VPN tunneling. Dropping the RTP down to 20ms still gains 80 percent overhead, compared to 20 to 30 percent with adjustments in encryption and authentication and a doubled RTP. SRTP, meanwhile, yields just five percent extra overhead.

Turning to a Sippy solution for VoIP VPN, meanwhile, offers some further benefits to users. One of the most frequently used VoIP protocols, Session Initiation Protocol (News - Alert) (SIP), has been shown to have trouble dealing with firewalls, as SIP uses random port numbers to set up connections. A VoIP VPN—especially a Sippy VoIP VPN—can work around the restriction that firewalls represent by acting like a normal data transmission, also allowing users that normally can't use VoIP calling on a particular network to do so by essentially converting that VoIP traffic to normal encrypted data traffic. This is largely owing to Sippy's combination of Sippy Softswitch technology with its use of VPN systems.

No matter what method of encryption is used here, it's clear that adding encryption to a VoIP solution is going to be a smart and very useful idea, offering the kind of safe, secure and simple communications techniques that businesses need to both get and stay ahead of the game.