Digium
Where it's based: Huntsville, AL
When it was founded: 1999
Website: www.digium.com [1]
Why it's Fierce: Digium single-handedly defined open source telephony with Asterisk and is now almost always on the checklist for many businesses when it comes time to sit down for a discussion of IP telephony. Other open source competitors compare themselves to Asterisk and - perhaps the ultimate complement - Cisco has an internal marketing document loaded with talking points against the solution.
While it positions Asterisk as a customizable "telephony platform" to build solutions on rather than just a vanilla IP PBX, Digium continues to steadily evolve as it hires the best and brightest programmer and developer talent as well as seasoned executives. Partnering with Skype was a Fierce move and last year's acquisition of Switchvox gave the company a needed boost in providing a flexible SMB turnkey solution for resellers. About the only thing missing to complete its Cinderella story would be a blessing by a Fortune 500 IT powerhouse.
Links:
[1] http://www.digium.com
[2] http://www.fierceenterprisecommunications.com/special-reports/dialogic-top-voip-company-2008-fiercevoip-fierce15
[3] http://www.fierceenterprisecommunications.com/special-reports/fiercevoips-fierce-15
[4] http://www.fierceenterprisecommunications.com/special-reports/divitas-networks-top-voip-companies-fiercevoip-fierce-15