Skype has launched an addition to its range of VoIP products with a new offering, Skype for Business.

The move builds on Skype's existing small business offerings with a dedicated website, and support, new hardware and new features to better manage groups of users and pre-paid accounts.

Unlike with consumers, who use Skype mainly to make free calls to other Skype users, businesses are paying for the ability to call out to PSTN numbers from a PC. The cost is about US$35 a year.

Standard Centrex lines run about US$50 a month per line. Other VoIP players such as Vonage offer a sweet spot on the price scale for SMBs at about $40 a month.

Skype's vice president of global market marketing, Saul Klein, said the aim of Skype for Business was the "neglected" small office with between one and 10 people. "[We want to] be the champion of micro-business," he added.

The business opportunity is huge, analysts say. Such hosted VoIP services for business are expected to be worth $785 million in 2009, up from $233 million last year, according to the Yankee Group.

Rivals are not standing still. AOL has said it will offer a product with its upgrade of Instant Messenger this year that will be aimed at small business. Yahoo and Microsoft struck a deal last year to work together on IM for Microsoft's Live Communications Server.

But small businesses would need to wary about security. Earlier this week, the Burton Group warned that the hype about Skype was brushing aside some serious security concerns about the technology.