Siemens this week is expected to launch a new version of its flagship IP PBX, boasting higher capacity, better sound quality, and improved failover and reliability features.The\u00a0HiPath 4000\u00a0Version 2.0 triples the maximum number of users on an IP PBX to 12,000, up from 4,000 on the previous version. It can support IP phones, TDM handsets or a combination of the two. A new distributed call-processing architecture lets remote office IP PBXs in a HiPath 4000 system take over as the main call-control node in the event of a hardware or software failure on the main HiPath box.The company also is launching the OptiPoint 410 IP phone. The phone employs a voice-over-IP (VoIP) coder\/decoder that delivers higher-quality voice than traditional TDM phone systems, according to the company (see below). The phones can be loaded with a\u00a0Session Initiation Protocol\u00a0stack or Siemens' proprietary VoIP protocol, and support\u00a0802.3af\u00a0power over Ethernet.Version 2.0 of the HiPath 4000 IP PBX is built on a new compact PCI (cPCI) chassis, a 19-inch rack-mount enclosure used in carrier telecom equipment, as opposed to the 30-inch chassis that the previous version used.Processor blades can be inserted into the chassis to support IP,\u00a0TDM\u00a0or a mix of endpoints. Up to nine HiPath 4000s can be networked to provide a single system, with support for up to 100,000 endpoints.Siemens also is announcing a remote office system, the Access Point 3700. Also a cPCI chassis, the AP 3700 would sit in a branch office and provide call control for TDM or IP handsets, and link back to a HiPath 4000 at the main site via an IP WAN.The HiPath 4000 runs Siemens' ComScendo software on top of an embedded Unix operating system. The ComScendo software provides call control (via Siemens' proprietary CorNet IP protocol) features and system management functions. The IP PBX also runs a quality-of-service monitoring function that measures latency across a WAN. This can let a HiPath 4000 switch trunk lines over to a TDM, or a back-up IP network if WAN congestion exceeds a user-determined level, or fails completely.The HiPath 4000 and AP 3700s also can back up each other during hardware failures. If the central-office HiPath 4000 is unavailable, centralized call control across the network can fail over to an AP 3700 in one of the branches. Calls would be temporarily routed and processed through the branch-office IP PBX until the main-site HiPath was brought back up. HiPath 4000 chassis also can be fitted with a back-up call-processor blade for an extra layer of redundancy.The University of Texas Southwestern Medical Center in Dallas runs a HiPath 4000. The facility, which occupies a dozen buildings across a two-mile campus, is replacing an old Rolm 9000 PBX (Siemens bought Rolm from IBM in 1992). This requires a mix of TDM and IP as the Rolm PBX is phased out and the HiPath phased in, says Elwyn Hull, telecommunications director at Southwestern Medical Center.The Rolm-to-Siemens migration will take about five years, as the medical center's 10,000 doctors, nurses and staff are shifted from TDM to IP. Hull says this large window of time was necessary as the center upgrades its network to be VoIP ready. Currently, 600 users are on TDM HiPath phones, and about 150 in two remote offices are on OptiPoint IP phones.Hull says he chose the HiPath 4000 for the VoIP migration because of its ability to scale and to mix TDM and IP. "Our clinics are critical areas," Hull says. "We have faith in [VoIP], but we're just not comfortable with running pure IP in there yet." Siemens also was the only vendor that could integrate features from the Rolm PBX across the HiPath box, he adds.The Siemens HiPath 4000 competes with IP PBXs such as 3Com's VCX enterprise softswitch, Alcatel's OmniPCX Enterprise, Avaya's S8700 MultiVantage platform, Cisco's CallManager and Nortel's Succession IP PBX platform.The HiPath 4000 Version 2.0, AP 3700 and the new OptiPoint 410 phones are expected to be available in the first quarter of next year. Pricing is expected to be about $140 for the OptiPoint phones, and about $400 per line on the HiPath 4000. Voice mail systems, unified messaging and other applications will be available separately. OptiPoint 410 and G.722Siemens' new OptiPoint 410 IP phone uses the International Telecommunications Union standard G.722 codec for voice digitization and compression. G.722 has a compression rate of 48K bit\/sec, while most IP telephony gear on the market uses the uncompressed G.711 codec (64K bit\/sec) or the G.729 codec, which transmits at 8K bit\/sec. According to Siemens, G.711 and G.729 VoIP phones, as well as most standard TDM voice systems, transmit as 3.3-KHz narrowband voice signals, while the G.722 codec transmits as 7-KHz wideband. Siemens says the broader bandwidth helps improve the clarity of phone conversations.