John Brown boards the 07.43 from Surbiton and strikes up a conversation with his wrist watch. He tells it to divert his office phone to voicemail for the morning, asks for the latest stock prices from the Hang Seng, dictates a couple of letters, then tells the watch to call his bookmaker.
If he did this today, the only effect would be that he'd get the train compartment to himself, since he would be taken for a madman. But within five years, his only problem might be how to make himself heard above the sound of his fellow passengers all bellowing at their own watches.
Much of the necessary technology for this scenario already exists. Mobile phones like the Genie or Spark from Philips can understand up to a dozen pre-recorded short dialling instructions, such as 'office' or 'bookie'.
Philips claims phones with vocabularies of 50 or more words are already feasible.
Japan's national telephone company, NTT, piloted a voice-controlled, watch-sized phone at the winter Olympics, and Seiko has just launched a wrist watch computer, the Ruputer, in Japan.
Swatch says a GSM version of its Swatch Talk wrist watch phone will go on sale next year, although this will not be voice controlled. And the first generation Swatch Talk, which operates as a domestic cordless phone with a 300m range, should be in the shops by Christmas.
But effective voice recognition requires a lot of computing power, which is difficult to provide in a small mobile device - hence the limited vocabulary of phones such as the Genie.
The alternative is to put voice recognition software on the phone network.
This enables more fancy functions and allows users to take advantage of technology updates without buying another phone. It will give the ability to deploy applications that were previously impracticable on a touch-tone phone.
You would be able to say: 'Get me the latest on the FTSE Index', or 'Transfer calls from my office to my mobile phone between 3pm and 5pm', or 'Play my last three voicemail messages from Bill'. You would have the beginnings of your own voice-controlled personal assistant, with scheduling, diary, address book and so on.
Voice-controlled phones would also be much safer for drivers to use.
According to the Transport Research Laboratory, dialling a number can be as distracting as trying to read a map while driving. Voice-controlled dialling needs no hands.
In February and March, Cellnet piloted a service which lets customers dictate documents via their mobile phones. These were converted using a voice recognition system from British software company Speech Machines, checked by human operators then emailed back to the customer. Cellnet hopes to launch the service later this year, subject to agreement with Speech Machines.
So if you get a letter which begins 'diddle-de-dum, diddle-de-dum', you'll know where it was composed.
Paul Bray is a freelance IT journalist.
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