I have long held the belief that mobile handsets have a lot more room to go to extremes than what we have seen even today. The fundamental question is do we want or need a converged device and then what parts of the device are converging different modes and devices. Just force fitting more and more functionality into the same old candy bar, clam shell or slider is only yielding marginal improvements and often that improvement is received by most users with a reaction that ranges from ignorance to disdain. Touch screen phones such as the LG KE850 (Prada phone) or the iPhone are taking data centric devices to the next level (or at least we hope so.) What is happening on the voice centric side? Not much from what I can see. Maybe heres a suggestion.
Develop a voice centric, voice controlled mobile phone. First split the microphone from the main device. Use a Bluetooth headset as the only communications mode to the device. The body of the phone houses the radio transmitter, the electronics and battery of the device. Have a small screen for caller ID or mobile applications and last but not least eliminate the keyboard. Both the headset and body should have a mini-USB for as combined power/data interface with the capability to charge one with the other and to daisy-chain them to charge with one USB port/charger. A device like than can surely get below 3 ounces and be easily places in pant pockets or a purse.
So how do you use this device? You talk to it! Voice activated dialing and voice activated controls for the navigation of the various functions of the phone are finally at the stage where they are working well enough for the mainstream user. Call Jack, activate music player, play songlist two, give me directions from here to the following address and the device will execute the command and provide the information in voice form. Even mobile web pages can be read to you, for the pictures or reference one can use the screen. For more complicated data entry/transfer give the backup option use a computer with USB connection to transfer the information, such as a phone/address book or transfer music to the device.
The only downside to a device like this is that you give up on mobile games and that you may have to scramble for your Bluetooth headset when the phone rings.