By Cassimir Medford

In a significant departure from its long-established norm, Cisco Systems said Friday that it plans to acquire Five Across, a startup that markets a social networking system for corporations to interact with online communities of interest.

The announcement comes one day after Mike Volpi, the man most had considered Cisco’s CEO-in-waiting, abruptly resigned for “personal reasons.”

Cisco, one of the world leaders in the networking equipment market, tends to acquire companies with technologies closely related to its core business: the transmission of data, voice, and video across digital pipes.

Three-year-old San Francisco-based Five Across does not fit that bill.

The company, which has only 11 employees and took $2 million in venture funds from Granite Ventures and Adobe Ventures, is pretty far removed from the networking hardware business.

“Some of these things are personality driven by a specific unit within the company, but it is also part of a broader trend,” said William Lesieur, director of Technology Business Research. “It shows that Cisco is reaching beyond its traditional roles.”

The broader trend Mr. Lesieur is referring to is the convergence of content and communications in applications such as software-as-a-service and other forms of application hosting.

“The telecom equipment industry understands that it will not sustain its business model through hardware,” Mr. Lesieur said. “Its growth possibilities will shift to software and hosted services, but Cisco’s traditional role is to enable others to do this kind of thing.”

Shares of Cisco fell $0.35 to $27.79 in recent trading.

Big Step for Cisco

Five Across started as an instant messaging company focused on setting up small and medium-sized companies to collaborate via IM. That focus has broadened to include social networking. Businesses can use Five Across’ technology to add social networking features to their web sites.

“Cisco believes the network is the platform for organizations to connect with their constituents and for individuals to connect with each other,” Dan Scheinman, senior vice president and general manager of the Cisco Media Solutions Group, said in a statement.

“With the acquisition of Five Across, Cisco is taking an important step toward helping its customers evolve their web site experience into something more relevant and valuable to the end user,” Mr. Scheinman added.

In its heyday in the nineties, Cisco left applications and services of this sort to its customers. The applications created demand for Cisco’s routers, and Cisco was quite content to play the exclusive role of equipment supplier, Mr. Lesieur said.

“Acquiring Five Across is a big step forward for Cisco, which traditionally would just inject money into small startups like this one,” said Mr. Lesieur.

Executive Exit

Cisco has been in change mode for some time, but few of its changes have the impact of Thursday’s news that Mr. Volpi, head of Cisco’s router and service-provider operations, abruptly resigned.

Mr. Volpi was generally considered to be the executive being groomed to replace Cisco CEO John Chambers.

“Mike Volpi’s departure most likely has nothing to do with the Five Across acquisition, but it does most likely reflect some of the overall uncertainty in the industry,” Mr. Lesieur said. “It reflects the unraveling of some of Cisco’s traditional assumptions. Its ecosystem has to change as the market realities change.”