Here’s where to turn when selecting a VoIP provider. Many of these vendors will be familiar, since most also sell legacy phone systems Most of these vendors offer a mix of TDM-based and VoIP products so that VoIP can be applied where it provides the most benefit. For this reason, enterprise customers tend to choose the same vendor that sold them their legacy telephone equipment.3Com One of the first IP telephony players from the data side, 3Com offers IP telephone systems for small, medium, and large businesses. Its enterprise VCX V7000 product interoperates with legacy PBX’s and accepts legacy handsets for a gradual migration.Alcatel This second-tier player offers IP phone systems with support for legacy devices to enable a gradual migration to IP. Its OmniPCX Enterprise IP PBX features native SIP (Session Initiation Protocol) support and Web services interfaces to integrate voice into business applications. Avaya One of the biggest players in the legacy and IP telephony space, Avaya sells legacy, hybrid, and complete IP phone systems. Avaya’s Extension to Cellular feature rings incoming calls on desk and cell phones simultaneously and provides cell phones with office phone functionality.Cisco The principal IP telephony player from the data side, Cisco offers complete IP enabled phone systems that can bridge to existing phone systems and a variety of phone types including wireless and XML enabled handsets.Mitel A second-tier vendor that offers hybrid and complete IP phone systems, Mitel offers a unique Your Assistant app, which provides presence information and lets users manage all their communications from one interface. A YA Pro softphone offers multiparty videoconferencing. NEC This diverse tech giant offers phone systems with a modular architecture that supports legacy, hybrid, and completely IP-enabled phone systems.Nortel Networks One of the biggest players, Nortel offers legacy, hybrid, and complete IP enterprise phone systems to allow a gradual or complete migration to IP. Its Meet Me Conferencing application adds collaboration, presence, messaging, and video calling services and an i2050 Mobile Voice client runs on a PDA.PingTel This IP PBX supplier recently went open source with SIPxchange, a SIP-based, customizable IP telephony platform that runs on standard server hardware and includes WebEx, along with tools for integrating VoIP with enterprise applications. Siemens A major player in the legacy and IP space, Siemens offers hybrid and complete IP solutions for a gradual migration to IP. HiPath OpenScape is a suite of presence-aware conferencing applications and middleware that can be integrated with IBM, Microsoft, and SAP data application platforms.ShoreTel Formerly Shoreline, it offers all-IP phone systems using an architecture of distributed, centrally managed IP voice switches. Switches can also accept Shoreline’s own analog phones.Spectralink A key player in voice over Wi-Fi, SpectraLink offers wireless handsets for both legacy and IP phone systems through service, equipment, and application providers. Toshiba A provider of legacy, hybrid, and IP-based phone systems, Toshiba’s major products include the Strata CTX100 and CTX670 IP-ready PBX systems.Zultys This IP PBX vendor provides VoIP products that combine several functions in one box and work with third-party SIP handsets. Technology Industry