Adecade ago, telecoms and IT were separate worlds. The mobile phone had not long gone digital and the office handset was a resolutely single-function device, tied to a proprietary system.

But the communications options open to the average office worker continue to proliferate and threaten the dominance of the office phone system or PBX. The desk phone has been joined not just by the mobile, but by instant messaging, internet telephony and networks such as Skype, softphones, conferencing systems and video.