Combine the freedom of wireless networking with the flexibility of VoIP and you've got a workplace revolution on your hands, but it's still early days for mobile VoIP.
Wireless VoIP deployments take advantage of an organisation's Wi-Fi network to allow employees to utilise the benefits of VoIP, such as presence and unified messaging, without being tied to their desks.
It's also possible to make VoIP calls over mobile phone networks, but the high cost of mobile data in countries such as Australia often makes this impractical. This is starting to change, with the X-Series plans on Hutchison's 3 network in many countries offering cheap data packages and unmetered Skype calls from mobile handsets.
The use of Wi-Fi-based VoIP can be divided in to two main categories - those systems using dedicated wireless VoIP handsets and those using "dual mode" handsets - running VoIP software on Wi-Fi-enabled mobile phones. Dual mode handsets are a classic example of the convergence of communications technologies. When you're in range of an accessible Wi-Fi network, dual mode handsets let you bypass the mobile phone network to make and receive VoIP calls. Obviously there are significant call savings to be made when you can divert outgoing mobile phone calls through your VoIP network.
Analysts staring into their crystal balls are making varying predictions about the future of dual mode handsets.
Juniper Research says that dual mode handsets are going to be big. It predicts the worldwide market for VoIP-over-Wi-Fi handsets will grow to almost US$70 billion by 2012, but that only 2 percent of this will be WLAN-only handsets. In other words 98 per cent of Wi-Fi phones will be dual mode handsets.
Report author, Basharat Hamid Ashai, says that "the dual mode handset market will pick up much faster in the coming years than the single mode Wi-Fi handset sector. The handset market is moving to a stage where no one wants to carry two or three devices in their pocket, so the ability to have a single device for all calls is a compelling proposition. Most single mode VoIP over Wi-Fi handset manufactures are actively either designing or planning to ship dual mode phones".
Alternatively, analysts group Ovum says there is too much hype around dual mode phones in the US. It predicts that only just over 2 per cent of mobile subscribers will have purchased dual mode services by the end of 2010.
"Equipment vendors have been fixated on dual mode phones as the key form of fixed-mobile convergence, but the people responsible for implementing this - the carriers - are really skeptical that the devices and solutions are ever going to be ready for prime time," says Jan Dawson, the report's author and VP of Ovum's US Enterprise Practice.
Of course the carriers are sceptical, they're the ones most threatened by dual mode handsets.