Established IP telephony vendors are not being adversely affected by the arrival of unified communications offerings from Microsoft and IBM, analysts report.

Unified communications mobility solutions are identified as potentially a " primary threat" to desktop IP phones, according to IDC.

"By the end of 2007, Microsoft and IBM had shipped their first versions of UC solutions," said Nora Freedman, a senior analyst in the enterprise networks group at IDC.

"So IP telephony vendors no longer had to speculate about what effect the desktop-based collaborative environments with IP telephony would have."

IDC identified Cisco, Avaya, Nortel and Siemens as the leading vendors in the worldwide IP PBX market based on end-user revenues in 2007.

Cisco gained the most market share in the IP PBX market, while Alcatel-Lucent lost the most market share relative to 2006. The others had nominal changes in market share year over year.

The IDC study noted that Cisco maintained its dominance in the market for IP phones as the leading vendor in terms of hardware desktop IP phone shipments and end-user revenue.

As seen in the IP PBX market, Alcatel-Lucent suffered the greatest decline in year-over-year market share based on end-user revenue for IP phones.

IDC's research revealed that some potential threats to the IP PBX market, including desktop collaborative environments, open source IP PBX and hosted VoIP services.