Empirix -- Be Confident.
Empirix is the leading provider of VoIP, contact center, and web application testing solutions. Empirix helps organizations adopt complex communications solutions with confidence

Internet Telephony Magazine -- The destination for Information Technology Professionals
Internet Telephony focuses on providing the information that will help you take advantage of the convergence of voice, video, fax, and data that has revolutionized the world of telecommunications. 

voip-info.org -- A reference guide to all things VOIP
voip-info.org provides a Wiki that covers everything related to VOIP, software, hardware, service providers, reviews, configurations, standards, tips & tricks and everything else related to voice over IP networks, IP telephony and Internet Telephony.

VoIP Magazine -- The IP Communications Authority
VoIP Magazine addresses the business case and technical issues enterprise customers face as they deploy and manage VoIP systems and converged IP communications networks within the enterprise, while at the same time providing service providers with the information and tools they require to best serve their enterprise customers.

VoIPTroubleshooter.com -- Free problem resolution tools for network managers - including Online Diagnosis Tools, Pre-Deployment Tips, Voice over IP Basics, Voice Quality Metrics, and Decoding Packet Metrics.