You may want to try Avaya’s web site, http://www.avaya.com. They are adopting a similar approach to converged voice and data networks where most of the platforms are primarily COTS HW and operating systems. They are focusing more on the SW aspects of voice call processing. Don’t know if there are any good white papers available on their approach or not.
AVAYA does not have a real PCBX yet. There approach like Dana says is similair. The IP600 is proberbly the product that fits the profile. Most of the technical specs are only availible from the web if you are a business partner
Intel is something you’re may be interesseted in aswell:
Intel converged communication platform ftp://download.intel.com/apac/eng/network/ICCP_over.pdf