IP telephony start-up Zultys Technologies is expected this week to announce a small-office version of its IP PBX that can cost less than circuit-switched telephone key systems, or small PBXs, while providing converged IP-based voice\/data applications that aren't supported on traditional small-office systems.IP telephony start-up\u00a0Zultys Technologies\u00a0is expected this week to announce a small-office version of its IP PBX that can cost less than circuit-switched telephone key systems, or small PBXs, while providing converged IP-based voice\/data applications that aren't supported on traditional small-office systems.The MX250 is a hardware\/software bundle that integrates IP telephony, and WAN routing and security, into one embedded-Linux\u00a0appliance. The MX250 supports up to 250 phones. The vendor touts the box as a complete IP telephony product for small businesses, or as a distributed site IP PBX for larger companies with many branch offices.The MX250, like Zultys' larger MX1200 (1,200-phone box introduced in February), uses\u00a0Session Initiation Protocol\u00a0natively for its call-control technology, letting the device work with any standard SIP-based hardware phone (from Alcatel, Cisco, Mitel, Nortel and PingTel) or with SIP-based softphone clients, including Microsoft's Windows Messenger software. Some vendors offer SIP as an add-on protocol, or encapsulate SIP inside proprietary or\u00a0H.323-based protocols, on their IP PBXs.SIP technology also is incorporated into several applications on the MX250. The appliance can act as a messaging server for a PC-based client application that incorporates voice mail access with Microsoft Outlook e-mail, along with instant messaging and presence. A separate application, say for a corporate receptionist, can be used to track the availability of employees, via phone, e-mail or cell phone, and forward calls and messages accordingly.A voice mail system is included in the MX250. Messages, in the form of WAV files, can be stored on the box's internal hard drive or on an attached storage device, such as tape drive or network-attached storage appliance. The MX250 can terminate fax messages and route faxes to Outlook in-boxes.Built into the MX250's Linux kernel are WAN routing and firewall modules. Also included are VPN services, which can let remote users with Internet connections log into the box securely for phone access and to use messaging applications as if they were in the office, the company says. The box uses key exchange technology 128-bit Advanced Encryption Standard and Diffie-Hellman.Along with encryption, the MX250 uses the standard G.729 voice-over-IP (VoIP) compression codec to support remote users. G.729 compresses traffic for WAN IP phone users from an uncompressed bit rate of 64K bit\/sec (which could overwhelm some dial-up or broadband connections) down to 8K bit\/sec. On LAN connections, where bandwith is plentiful, the MX250 processes traffic uncompressed for greater clarity.The hardware in the appliance includes dual IBM PowerPC chips and an embedded Linux operating system from Monta Vista Software. Two MX250s can be set up for redundancy, letting one box take over if the other fails.The MX250 will compete with small-office VoIP gear such as 3Com's NBX100, Avaya's IP Office, Cisco's ICS-7700 series and MCS-7800 series, Nortel's Business Communications Manager.The MX250 costs $44,000 for the appliance hardware, applications and Zultys Zip2 SIP-based IP phones for 250 users.