Two weeks after Microsoft said it would acquire Skype, the voice over IP company has begun cutting its ties with the open-source world. Asterisk was the first partner cut loose.

Skype decided not to renew its agreement with Digium, which allowed Asterisk, the open-source telephony system, to be integrated with the Skype service, Digium said May 25 in a letter to users. Digium is behind most of the work on Asterisk and sells commercial products based on the platform. Skype for Asterisk uses some proprietary code from Digium to connect the two products.

"It includes proprietary software from Skype that allows Asterisk to join the Skype network as a native client. Skype has decided not to renew the agreement that permits us to package this proprietary software," according to Digium's letter.

Skype for Asterisk sales and activations will end on July 26, but Skype has promised to continue supporting and maintaining the software for two more years. Skype may extend this time period "at their discretion."

Many businesses and governments around the world rely on Asterisk for its free and flexible PBX to power their VOIP deployments. The integration with Skype gave access to low-cost voice and video calls without complex integration. After July 26, new Asterisk users will not be able to connect to the Skype network.

Skype may be moving away from Asterisk because Microsoft is expected to launch a Microsoft-hosted version of its Lync unified communications server this summer. Asterisk competes directly with Lync.

Digium may have seen this one coming, as the CEO predicted shortly after the $8.53 billion deal was announced on May 13 that Microsoft may "wall-off" Skype from competing products. Microsoft's tendency toward "notoriously proprietary tactics" will slow the development of Skype as a business tool, Danny Windham, Digium's CEO, wrote on the company blog.

"Microsoft plus Skype equals Microsoft," Windham wrote.

While it may be easy to pin down Skype's decision as yet another example of Microsoft trying to shut down the open-source community, Tim Panton, a Skype developer, pointed out on his blog that Skype for Asterisk has been dying slowly for a while because of issues with scalability and maintenance. Skype had "hobbled" the product with a number of license restrictions and the company delayed development, according to Panton.

"Skype probably never envisaged renewing, so when it came due, they pulled the plug," Panton said.

"I do love a good conspiracy, and it would be great to pin this on Microsoft," wrote Dave Michels, president of Verge1 Consulting, specializing in PBX strategies. However, Michels noted that it was unlikely Microsoft was calling the shots when the deal hadn't even closed yet.

Michels also pointed out that while Asterisk is open source, Skype is not, so claiming Microsoft will ruin Skype because of its anti-open-source stance is "hypocritical jabberwocky." Skype uses its own clients, its own codecs, its own signaling and its own firmware licensed to hardware partners. It does not interface with any other networks or equipment other than basic voice services. "If anything, Skype might teach MS a thing or two about being proprietary," Michels said.

A Gartner analyst agreed that Skype's decision had nothing to do with Microsoft. This is a sign Skype will open up its service to other telephony platforms via Skype Connect, Steve Blood, research vice president and agenda manager at Gartner, told eWEEK. While Skype for Asterisk was a bit deeper than what Skype Connect (formerly Skype for SIP) offers for other telephony platforms, it's a "stronger business proposition" for Skype to offer more customers Connect than to support a proprietary product for a specific vendor, according to Blood.

"I don't think Skype for Asterisk was compelling enough, nor did it generate enough money for Skype to continue to support it," Blood said.

Skype Connect currently works with telephony systems for Avaya, ShoreTel, and Cisco, among others. Digium will be validating Skype Connect next month, according to Blood, so Asterisk customers will continue to have some Skype support.