Unison now offers both desktop and server versions of its unified communications software on Ubuntu Linux. Unison's software, which runs exclusively on Linux server OSes but can run on either a Linux or Windows desktop, already runs on Red Hat Enterprise Linux and CentOS.

New York-based Unison, which launched its software last July, has both an advertising-supported free version of its platform and one it offers for US$50 per user, per year. In fact, Ubuntu Linux, which is commercially sponsored by Canonical, is one of the advertisers in Unison's software.

The Unison Server and Unison Desktop products give companies a cost-effective alternative to software from Microsoft or IBM to run a unified suite of e-mail, telephony, voicemail, instant-messaging and other communications and collaboration applications, according to Unison.

Unison's client/server architecture has similar characteristics to Microsoft Exchange/Outlook and IBM Lotus/Domino. In addition to e-mail, directory, telephony, instant-messaging, calendaring and contacts capabilities, Unison also includes antispam and antivirus software.

Unison's software is best suited for small to medium-sized businesses with about 20 to 2,000 employees, which may find deploying unified communications using software from IBM and Microsoft cost-prohibitive, Unison Chief Marketing Officer Rurik Bradbury has said.