Secure VoIP has arrived

A start-up called Net6 claims that its virtual private network products offer companies high-quality voice communications over any network from anywhere.

On Tuesday, Net6 announced several enhancements to its VPN gateway that enhance the quality of service for all voice over Internet Protocol (VoIP) traffic traveling over a Secure Sockets Layer VPN.

SSL has become a popular alternative to VPNs that use IPsec encryption and tunneling for connecting remote workers to corporate networks. Because SSL VPNs give access through a standard web browser instead of through an IPsec client running on each device accessing the network, many companies find SSL to be much easier to deploy and manage.

But SSL VPNs aren't perfect for every situation. For one, they rely on TCP (Transmission Control Protocol), which works well for data applications but not as well for latency-sensitive traffic such as voice. TCP uses packet retransmission, which means that packets can be delayed en route to their destination. This is not a problem for basic email or file transfers, but for voice and video calls, it degrades quality significantly.

Net6 has developed technology that it says will get voice and video traffic to its destination securely and without delays. The Net6 device sends false TCP acknowledgements so that the sender continues sending packets. Murli Thirumale, Net6's chief executive officer, admits that some packets may be lost along the way but he said that has little effect on voice quality.

"Because of the real-time nature of voice, losing a few packets doesn't impact quality much," he said. "You may not get a crystal-clear hello, but you'll hear the voice in real time and not experience any delays."

Net6 isn't the only SSL VPN equipment maker to tweak its solution to carry voice traffic. Juniper Networks says its SSL VPN gateway product, Network Connect, has been supporting voice for over a year.

But Juniper and other SSL VPN players say they haven't seen much demand for VoIP over SSL yet. Aventail, another prominent player in this market, said it will offer VoIP over SSL later this year.

Chris Hopen, Avantail's chief technology officer, said: "VoIP is an important feature coming in the near future. But the mass market demand is not quite there yet."

Aventail and Juniper also said customers are much more concerned about integrated security features that ensure users are not connecting to the network through infected end devices.

Vivian Ganitsky, Juniper's senior manager of product management, said: "While Net6 may offer a network connection over SSL, they do not have the end-point security measures of our established SSL VPN. This is important to customers when providing a network connection via any browser."

Marguerite Reardon writes for CNET News.com