This is the year that enterprise IP telephony hits full stride with advanced product features and more large-scale user deployments, experts predict.Early adopter shares VoIP lessons learnedLessons from the Department of Education. Remote-office resiliency, wireless voice over IP, and expanded server platforms and protocol support are some of the items IP PBX users want - and VoIP vendors say customers can expect - in 2003.Sales of the equipment reached approximately $1.4 billion in 2002, according to Synergy Research Group, which expects the market to reach $5.2 billion by 2006. Many VoIP companies are now on their third and fourth generations of gear, and large integrators such as IBM Global Services are fortifying offerings with packaged installation and management services for enterprise IP voice.Support for Session Initiation Protocol (SIP) is on the road map for a few IP telephony vendors in 2003. SIP is an IETF standard that will let customers use IP networks to establish sessions, instead of just phone calls, which could include voice, video or instant-messaging communications.The protocol also can be used in "presence " applications, where users list themselves as available (similar to a "buddy list") via a SIP URL. This allows users to be reached via whatever SIP-enabled technology is available: phone, videoconferencing or instant messaging. Some industry observers see the protocol as the successor to H.323, which is used widely in corporate IP telephony phones and IP PBXs today."SIP is the key to the maturation of the IP telephony market," says John Ridley, senior technical architect at Coca-Cola Enterprises in Atlanta, who currently uses an Avaya-based PBX phone network and\u00a0TDM -based equipment from other vendors.Ridley says the delivery of SIP by major IP telephony players is something he's been waiting on for a while. "Once the standard is there, then telephony will be like Ethernet . . . cheap components that are interoperable," he says.Several IP PBX vendors have announced SIP-based IP PBXs, including\u00a0Nortel\u00a0and Mitel, while others, such as\u00a0Avaya\u00a0and\u00a0Alcatel, have said SIP will be a part of their IP telephony stratetgy in the near future.\u00a0Cisco\u00a0offers a SIP-based phone, but no native support for the protocol on its\u00a0CallManager \u00a0phone server.Alcatel and Polycom are two companies that have made SIP support a priority for 2003. Alcatel expects to announce support for SIP phones for its hybrid IP\/TDM\u00a0OmniPCX \u00a0phone switch in the first quarter. Polycom, which had demonstrated a SIP phone at the Fall Voice on the Net conference, will have a production unit available this year. The company also is targeting a SIP-based IP teleconferencing station for release in mid-2003.Merging wireless and IP telephonyIn addition to SIP, some vendors and users will look to merge the worlds of\u00a0Wi-Fi\u00a0networks and IP telephony in the coming year."802.11 voice will be a very important application for the enterprise," says Bill Rossi, vice president and general manager of Cisco's wireless networking business unit. This marriage would seem logical, by most measures, because Cisco is the market leader in enterprise wireless LAN and VoIP."IP telephony is happening in parallel with wireless LAN," Rossi says. "[Enterprise users have] concluded generally that IP telephony is in their future . . . they also believe that mobility is important - being productive wherever you are."IP telephony in 2003Trends to look for from enterprise IP telephony gear makers:\u2022Platform expansionSome vendors will look to move their IP PBX platforms off of Windows-based servers and onto boxes running Linux, Unix or even proprietary systems.\u2022Wireless VoIPMakers of IP telephony gear will embrace wireless LAN and cell phone technologies.\u2022SIP proliferationStronger support for SIP, as vendors aim to handle converged applications.Rossi would not say what Cisco's specific plans were for Wi-Fi VoIP. Cisco CallManagers interoperate with wireless IP phones from wireless LAN rival Symbol Technologies and wireless LAN IP phone specialist Spectralink, but some users say a Cisco-branded Wi-Fi phone might be on the horizon.Mark Carrier, telecom manager at Crate & Barrel in Northbrook, Ill., recently oversaw a deployment of wired Cisco VoIP gear at his corporate office and says he was shown some beta Cisco wireless IP phones, along with Cisco's Aironet wireless LAN endpoint hardware."Wireless was something we are thinking about," Carrier says, adding that an IP phone that would let executives roam the building while remaining on the corporate phone - without using up cell phone minutes - could present a productivity and cost advantage.Avaya also offers wireless LAN IP phones from\u00a0Spectralink. The company also makes a softphone product that can be used on a PDA.Beefing up IP PBXsOther ways vendors will look to beef up their IP PBX offerings are the areas of remote-site survivability and the migration IP PBX software to new server platforms.Alcatel this quarter is expected to release "survivablity" hardware and software features for its routers and OmniPCX phone system. The new features will let remote Alcatel IP phones - which are tied to a centralized OmniPCX via an IP WAN - to remain working in the event of a WAN link failure.This concept appeals to\u00a0George Walsh, telecom administrator for the city of Brockton, Mass., where an OmniPCX recently was installed to support 250 city workers."One of the main things we're concerned about is disaster recovery," Walsh says.While he is working on getting the city up to speed with the basic features of the OmniPCX installed in Brockton's city hall, Walsh already is thinking about how to provide back-up phone access to remote workers. "If we lost connection to city hall, it is essential for us to be able to keep phone lines up and running at other offices," he says.On the issue of resiliency, Siemens says customers of its HiPath line of IP phone servers can expect to see a migration to "sturdier" operating system platforms."While not in the next release, we'll be expanding our server offerings for the [HiPath 5000]," says Joan Vandermate, director of product line management for Siemens' enterprise division. This will involve the porting of Siemens' Windows-based HiPath 5000 enterprise softswitch product to platforms such as Sun Solaris and Linux, and possibly a proprietary operating system in the future.According to Vandermate, the move into Unix and Linux support for Siemens IP PBXs came as a result of customer feedback, mostly from telecom managers who used phone systems that run on Unix-like operating systems. She says Siemens also is looking into developing a proprietary operating system for its IP servers over the next year or so, as a way to provide increased reliability and better performance.With Microsoft server operating systems, she says, "every time there is a new patch, which is often, we have to test it and certify it with our [IP PBX] software before we can tell our customers to deploy it."If Siemens had a homegrown operating system for its call servers, Vandermate says, "you'd lose some of the openness that may draw some customers to [IP telephony]," but in the long run, such a platform would be much easier on Siemens engineers and on Siemens customers, she adds.Avaya is taking a different route, as the company prepares a new platform for its IP telephony applications, based on Java 2 Platform Enterprise Edition and Microsoft .Net."We're breaking down our software products into reusable software modules," with the new products coming to market in the first quarter of 2003, says Karyn Mashima, senior vice president of strategy and technology at Avaya.This architecture will let users distribute call processing, unified messaging, call center routing intelligence and other IP telephony applications across various parts of a network, instead of having all functions in one centralized IP or TDM phone switch.