Microsoft reaches out to voice vendors

Microsoft is expanding its work with enterprise telephony vendors to make its Office Communication Server (OCS) 2007 work more closely with office phone systems.

On Tuesday, at the launch of OCS, the company unveiled a formal program to certify interoperability between IP (Internet Protocol) phone systems and OCS. As part of that, Microsoft discussed a specification to let enterprises migrate one building at a time to its software-based unified communications system and still have calls go across the organisation as if on the same PBX (private branch exchange). Two models of Cisco Systems' popular ISR (Integrated Services Router) branch-office platform will be among the products certified for this type of interoperability, according to general manager of Microsoft's Unified Communications group, Zig Serafin.

Microsoft's initiative, called the OCS 2007 Open Interoperability Program, will formalise work that has already been going on with some third parties. As that work had expanded, it had reached a point where it needed to be more organised, Serafin said. The idea was to let customers know what would work with OCS, and Microsoft would provide a table on its website where potential customers could check the certifications of third-party products.

Although promoted as an effort to coexist with the Internet Protoco (IP) phone systems now established or taking root in enterprises, the program also would make it easier for customers to migrate away from dedicated communications systems and phones themselves, the company acknowledged. Voice call control is new to Microsoft's unified communications system with OCS 2007, but the software giant envisions a day when separate platforms such as Cisco's CallManager won't be needed, according to industry analysts.

Cisco, Avaya and other vendors have already moved the voice call-control functions of traditional circuit-switched private branch exchanges (PBXes) into server software, but they sell that software along with IP handsets and other gear. Microsoft intends OCS, together with Office Communicator 2007 client software or special OCS phones made by Polycom and LG Electronics, to ultimately replace those dedicated systems.

There are three methods of interoperability that will be certified under the program.

- Computer Supported Telephony Applications (SIP CSTA) is based on a standard by the European Communications Management Association (ECMA). It lets users control calls through the Office Communicator client on the PC, though in most cases still using the handset and PBX.

- OCS Coexistence lets the user pick up a call on either the existing handset or a client that uses OCS, namely Office Communicator or a special OCS phone.

- Direct SIP (Session Initiation Protocol) interoperability allows for some parts of an enterprise to use traditional or IP PBXes and others to use OCS, with transparent connections between them using gateways, according to Microsoft. SIP is the emerging standard protocol for exchanging information on voice, videoconferencing and other communications sessions.

Microsoft had already certified gateway products from five vendors for Direct SIP interoperability, Serafin said. Among them are Cisco's Integrated Services Router 2851 and 3845. In fact, all ISRs with voice capability can interoperate with OCS, according to director of product marketing in Cisco's access routing group, Mike Wood, [cq]. Gateways from Dialogic also have already been certified. As a newcomer to telephony, Microsoft would take time to displace many standalone telephony systems, so interoperability would be critical, analysts said.

Most enterprises that adopt OCS still had phones connected to PBXes and would dial through the PBX, a senior analyst at Wainhouse Research, Brent Kelly, [cq], said. To start, most OCS users would keep their PBXes in place and take advantage of CSTA to gain the click-to-call benefits of OCS, he said.

"Right now, OCS doesn't have a voice model that's good enough for the enterprise," Kelly said.

However, there were a number of barriers to interoperability, too, IDC analyst, Nora Freedman, said. While Direct SIP interoperability was a good idea, it would take a long time to really work because SIP is so new, she said.

"We're still battling proprietary SIP extensions from all the notable vendors," Freedman said.

Meanwhile, CSTA could be a distraction for enterprises trying to make the transition to unified communications because it brought yet another standard into the picture, she said. And for now, it's hard for early adopters to get theses kinds of systems put together, she added.

"Now we have a wealth of product but a drought of system-integrator experience in this," Freedman said. Resellers were working feverishly to build up their expertise, she said.

Microsoft's plan for telephony was bold, looking to eventually eliminate OCS as a separate product and make it, and telephony itself, just a set of features in applications, Yankee Group analyst, Zeus Kerravala, said. But for the time being, the job at hand is making OCS work with existing phones, he said.

"The first phase is just to get it out there," Kerravala said.