In a recent article on the VoIP News Web site, Robert Poe described a new software product called SkyStone, which sounds like it may give Skype’s VoIP service its best chance ever of getting a strong foothold in the business environment. As a popular no-cost or low-cost way to make IP-based phone calls, Skype has appealed to consumers for a long time.

The company recently reached out to businesses with new business-oriented features in its latest client software. However, organizations remained wary of allowing employees to use the service on their company networks for a number of reasons.

SkyStone just may change all that. It integrates Skype calls with a company’s IP PBX system — as long as you use Cisco CallManager. (The company plans to release other versions that will support other PBX systems.)

From the user end, this means employees can use the same desk phones for Skype calls that they use to place other phone calls. From the administrator’s point of view, it’s easy to download and install on a server, and you can evaluate the trial version to decide whether it’s right for your company.

Poe’s article whetted my curiosity, so I decided to look a little deeper. Here’s what I found out.

Where SkyStone comes from

SkyStone is a product of Stonevoice, an Italian software company that develops applications for Cisco VoIP and unified messaging systems. Established in 2001, Stonevoice applications include IVR management, fax server, voice mail, call distribution, and call billing solutions. It also offers some free open source tools such as Stonevoice Translator, which you can use to translate its application suite to other languages.

How SkyStone works

SkyStone is a gateway product that can connect IP and traditional PBX systems to the Skype network so users can take advantage of Skype’s cost and features through the same physical interface they use for other calls. That means they can use their desk phones to call outside the office to people’s Skype accounts. Customers using Skype can call into the company via the Click2Call Web interface; and they can use the IVR, queuing, and other services used by regular PSTN callers.

Using Skype with a PBX system has been problematic in the past — Skype uses a proprietary protocol. But SkyStone supports standard VoIP protocols — SIP and H.323 — thus overcoming this obstacle.

While there are other Skype gateway solutions, many of them involve hardware-based solutions. SkyStone is a software module installed on a Windows computer. All that’s required is a network adapter and an Internet connection (unless you’re connecting to a traditional non-IP PBX, in which case you may also need a voice board).

Another cost-saving feature is the ability to configure an IP PBX to route international calls to SkypeOut in order to take advantage of its low calling rates. Skype becomes a “virtual carrier” for outgoing calls and saves the company money. Likewise, the SkypeIn service allows you to have a phone number for your Skype account that PSTN users can dial into, and SkyStone integrates both services into your PBX system.

SkyStone is appropriate for both the small and midsize business (SMB) market and the enterprise market.

What about security?

Of course, security is a big issue — and the big question confronting anyone who’s considering deploying any new software solution on an internal IP network today. In fact, security considerations are one reason that some companies don’t allow internal users to run the Skype client on their computers. You can set up the SkyStone Skype gateway in a DMZ or perimeter network to prevent direct Skype traffic from entering the protected LAN.

What will it cost?

That’s the big mystery at this point. Although SkyStone’s release date was June 29, no pricing information is available on the Stonevoice Web site, and the company uses an indirect sales model, licensing its products through authorized distributors and partners. You can find a list of authorized distributors on the Stonevoice Web site.

What are some alternatives?

PSGw (Personal Skype Gateway) is another software application designed to connect SIP or H.323 networks with the Skype network. It’s inexpensive — only $39.95 for the most popular SIP version. However, it only allows a single concurrent connection between Skype and the other VoIP network, making it inappropriate for business applications beyond those of very small businesses. But one selling point it that you can use PSGw with the Asterisk PBX.

Another way to integrate Asterisk and Skype is with ChanSkype on Linux. By installing Asterisk and the Skype client on a Linux box, you can make SkypeOut calls and receive incoming calls from Skype users (up to 30 concurrently). It runs on Fedora and Ubuntu Linux distros, and it does require a bit of technical savvy to set up. The corporate version costs $99 per port. (The personal version goes for just $19.)

A third option is Uplink, a Skype-to-SIP adapter made by NCH Swift Sound. You can download it from the company’s Web site; it costs $38.50 for a single professional license with no technical support. It’s a quick installation on Windows 98 and above, and you can use it to receive incoming Skype calls through a PBX, to dial out using your SkypeOut account, and to use SIP-based voice mail and IVR systems with Skype calls.

At the enterprise level, there are several choices:

  • SkyPBX Enterprise Bridge — an appliance-type solution from Industry Dynamics that integrates PSTN-based PBX systems with Skype
  • XSkype — a Skype gateway from Yeastar that supports 16 ports and uses Yeastar’s SKY8000 analog interface card installed in a PC running Windows XP or Windows Server 2003
  • VoSKY — FXO and FXS Skype gateway appliances that support Skype trunking and work with most analog and IP PBX systems


If you thought that Skype and your company’s PBX system would never be able to get along, think again. A number of products are now available that let you integrate the two in a way that’s almost transparent to your users. In addition, they can save your company big bucks by letting you take advantage of Skype’s low prices.

Deb Shinder is a technology consultant, trainer, and writer who has authored a number of books on computer operating systems, networking, and security. She currently specializes in security issues and Microsoft products, and she has received Microsoft’s Most Valuable Professional (MVP) status in Windows Server Security.

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