Almost three-quarters of business telephone lines shipped globally last year were at least capable of carrying IP traffic, new research reveals.

Frost & Sullivan's latest World Enterprise Telephony Markets report found that the market shipped more than 48.4 million lines in 2007 and estimates this to reach 62.1 million in 2013.

"Approximately 71 per cent of all lines shipped worldwide in 2007 were IP-capable," said Frost & Sullivan unified communications programme director Elka Popova.

"Replacement continues to be the main driver for market growth and, more specifically, IP telephony adoption."

Central America/Latin America emerged as the fastest growing region, followed by Asia Pacific.

Both these markets have strong telecom systems replacement activity in addition to greenfield deployments arising out of broad-based economic growth, according to Frost & Sullivan.

North America had the slowest growth, signifying high penetration levels of IP.

For the first time, IP telephony revenues exceeded Time Division Multiplexing telephony revenues in Asia Pacific in 2007.

EMEA remained the largest region in the world enterprise telephony market. Cisco experienced the fastest growth in EMEA among tier-one vendors.

However, IP penetration to the desktop remains low overall with North America boasting a relatively higher penetration than the other regions.

A major challenge for IP telephony vendors is that buying organisations prefer a phased migration to "forklift upgrades".

"Vendor consolidation might affect market confidence," said Popova. "A weakening supplier position will boost buyers' power even as strong indications emerge of a price decline."