Today, if you want to commission one mobile phone, you must decommission another.
Why must this be so? Cellphones are so cheap. Why can’t we have multiple active phones tied to the same number? A call to one would be a call to all of them.
Then you could have:
- one powerful PDA/communicator/GPS smartphone like the iPhone as your main device
- a tiny mini-cellphone/MP3 player to take running — an “iPhone Shuffle” (today I leave my phone behind)
- a backup cellphone to grab when you are rushing out the door, when you misplace or lose one
- a hands-free cellphone integrated into your car. No cables, no bluetooth coupling, no charging
- a cellphone built into your laptop computer. Your computer would “ring” when someone called. You could process voicemail visually from your desktop. It would provide data, voice and video call connectivity when WiFi wasn’t available.
- a couple of docked home cellphones that replace your existing land-line
Readers: We in the USA are mobile phone laggards. Does this capability exist anywhere in the world yet?

GrandCentral allows you to do this today. You can enter multiple phone numbers, and incoming calls to your GrandCentral phone number can ring all of your phones.
http://www.grandcentral.com/
It’s still by invitation only, though.
Thanks, David,
GrandCentral does allow the same scenarios, but without the simplicity or economy. You still need to buy, administer and think about multiple phone service plans.
The model I am wishing for is like webmail, where you have one account and can use any device to access it.