Last night, I left my cell phone in my car. As with most of my follies, I realized it a few oh-no-seconds after I got home, but only after I'd taken off my jacket, gloves, cap, shoes and socks. It was an unnecessary walk in below-zero temperatures, but it got me thinking about phones, identities, what's wrong about it all, and how it could be made better.
The problem is this: phones and phone numbers are tightly coupled together . No wonder people keep their phones close to their heart -- their personal identity is locked in it. If I don't carry my phone, there's no way to answer calls that I receive at that phone number. I can perhaps check voicemail from another phone, but still cannot make and receive phone calls under my own phone number.
Now compare this to email: if you go on a vacation without your own laptop computer, it is still possible to "borrow" someone's random computer and check your messages. The messages you send will have your ID (your email address) attached to them, and the people you interact with will have no idea what machine you used (and there is no need for them to know.)
Why can't we have a phone identity (our phone number) separate from the device (our phone) that is used to access it? If I forget my phone in the car overnight, I should be able to just add my phone identity to the home phone. That way, all calls that would have been received by my handset in the car will now be received at my home phone, and callers/callees will not know a thing. The next morning, I would re-establish my identity on my cell phone, and things will be back to usual.
I'm not a big fan of call redirects: that puts a temporary bandage on the problem instead of actually solving it. I don't want my identity routed to another identity: I want to be able to use my own identity wherever.
This would also open up the market for multiple-identity phones. A couple can add both their identities to a single home phone in the evening, while they carry individual cell phones during the day. Forgot your cell phone at home? No problem, just borrow a loaner phone from the office receptionist and use it all day long (just as you would borrow a loaner security badge if you forgot yours). It would also make it easy for a group of people to be able to respond to a single phone call, e.g. despatch services for emergencies. A group of doctors could share a single phone number. Whoever is on emergency call duty would add the group phone number to his/her cell phone, and remove it after the duty ends.
Historically, a phone number has been tied to a phone, mostly because of technical constraints, beginning with the days of the human-operated telephone exchange. Email has shown that identities (email addresses) can be independent of devices (computers), that many identities can share a device, and many devices can be used by a single identity.
It's an easy conceptual step forward to move to the many-to-many model instead of the current one-to-one. But there is a tremendous amount of change required of the infrastructure, and it won't be cheap. But since I don't happen to be in the business of implementing it (at least not yet!), so I'll just write about this idea and hope that someone picks it up. Maybe someone will listen, and like it, and implement it.
Then I won't have to walk out in the $#@*%$#^ snow to fetch a %$#%#$* cell phone.
 The more pedantic among us will point out that GSM phones keep the user's identity on a SIM card, and CDMA phones maintain a single ID tied to the IMEI number of a phone. Although possible, that does not make swapping identities across phones easy: in the first case, you must have your current phone handy, which does not help solve my problem of having left the phone in the car overnight, and the second one requires a long phone call to the carrier to make the change. Neither is as quick or handy as the method I envision.