Siemens this week is launching a high-end enterprise IP PBX that can host more than 100,000 IP phones from a single data center.Siemens\u00a0this week is launching a high-end enterprise IP PBX that can host more than 100,000 IP phones from a single data center.The HiPath 8000 IP PBX is targeted at very large companies that want to consolidate VoIP deployments into a large data center. Users and experts say a centrally hosted IP PBX can help businesses reduce VoIP operational costs.The HiPath 8000 is based on Siemens' HiQ 8000\u00a0softswitch, a Session Initiation Protocol (SIP) IP phone switch. The box is based on a Linux operating system, a change for Siemens, which until now has used Unix and proprietary operating systems on its PBX and IP PBX platforms. The Linux server runs call control and signaling applications on an IBM e-Series server with dual Intel Xeon processors.Siemens also has added extensions to SIP to let the HiPath 8000 support all Siemens' call features natively. Previous Siemens SIP implementations encapsulated the vendor's CorNetIP VoIP protocol inside SIP packets. Some industry watchers say full SIP adoption by IP PBX vendors has been slow because the core protocol supports only about 40 basic call features. PBX systems typically offer hundreds of features.Siemens says the changes it has made to SIP extend most of Siemens' call features to run on standard SIP endpoints. Siemens says any standard SIP endpoint, such as phones from Cisco, Pingtel or Polycom, can work on the system, as well as standard SIP softphone applications. Later this year, the company says, much of the work it did on SIP will be sent to the IETF as a contribution to the development of SIP.The HiPath 8000 is targeted at a small set of Fortune 100 customers looking to deploy voice as a centrally hosted application from a data center. For example, Siemens says that IBM is testing the HiPath 8000 for migration to an all-VoIP network, where more than 900 PBXs will be collapsed into around 11 data centers worldwide.Siemens' move to pure SIP on the HiPath 8000 could be attractive to some very large companies, says Brian Riggs, an analyst with Current Analysis. But the move also might cause confusion among Siemens' voice customers."Large enterprises are going to have to make a decision as to which [architecture] they're going to take," Riggs says. "This sends mixed signals to enterprises about what to do in terms of [VoIP] protocols. [Siemens] now has this high-end [VoIP] switch that's supposedly pure SIP, then down on the lower-tier products they're still selling CorNetIP," Siemens' proprietary VoIP protocol.Proprietary and open VoIP protocols have their merits, Riggs says. Proprietary protocols let businesses have more features, while standards-based options promise vendor interoperability and openness for application development.The HiPath 8000 is scheduled to be available in the third quarter, at a price of about $200,000 for the hardware and software. Per-user pricing, including phones and licenses, will cost about $300.