A good independent view was the January 2005 Business Communication Review Magazine of large scale PBXs. Here is a quote from the article.
“Avaya emerged as the clear winner in this year’s large IP PBX test, earning one of the highest scores we’ve ever recorded in our six years of testing these systems,” said Ed Mier, founder of Miercom. “Our comprehensive tests showed that Avaya’s IP telephony solutions deliver the highest levels of quality and reliability across the board, and received the top score in three of six criteria categories: architecture, features and endpoints. Avaya is at the top of its game, and we congratulate them on this win.”
Avaya was also came out on top in the March 2005 Network Computing VoIP systems evaluation of SIP interoperability
http://www.nwc.com/showitem.jhtml?docid=1605f2
A quote from this article
"Avaya's IP Telephony Solution took our Editor's Choice award because it provided the best interoperability, comprehensive management tools and a ton of features for the price."
As you may be aware, Avaya is releasing Communication Manager 3.0 which will bring IP telephony to a new level. If you would like details on how the Avaya solution compares to the competition, I would need to know what is important to your business (call centers, mobility, functionality, security, resiliency, etc) and I can provide you details. I can be reached at
cantwell@avaya.com or 786.331.0912.
Best regards