The enterprise telephony market continues its steady transition from circuit switching to packet switching technology, industry watchers reported today.

Newly published data from Infonetics Research indicates that worldwide TDM system revenue fell 15 per cent between 2004 to 2005 while IP PBX revenue rose 23 per cent.

The analyst firm's latest Enterprise Telephony report said that combined global TDM and IP PBX systems revenue totalled $8.1bn in 2005, a 12 per cent increase over 2004.

The sector is expected to grow 43 per cent between 2005 and 2009, when it will reach $11.6bn as organisations continue to move to VoIP.

In that five-year span, Infonetics predicts that IP PBX revenue will jump 82 per cent while TDM revenue will plunge 88 per cent.

"The PBX market came in at our expectations in 2005, and from a global perspective is doing very well," said Matthias Machowinski, directing analyst at Infonetics.

"Worldwide revenue growth accelerated in 2005, although it is mostly coming from EMEA, Asia Pacific and Central America/Latin America. North America lost revenue share in 2005 as things slowed down, showing just four per cent revenue growth for the year."

In EMEA Alcatel emerged as the leader in the fourth quarter of 2005 and for the full year, followed by Siemens.

Nortel led the North American IP PBX market in line shipments for 2005, followed by Avaya and Cisco. Cisco dominates the market for IP phones with 42 per cent unit market share in 2005.

The study also revealed that hybrid PBXs accounted for 65 per cent of 2005 PBX revenue, TDM 23 per cent, and pure IP 12 per cent.

The study expects that hybrids and pure IP devices will continue to increase market share until 2009 at the expense of TDM equipment.