You may not know it, but any cell phone -- whether it has an account with a carrier or not -- is able to call 911. You can leave one of your old phones (and a car charger) in your car if you just want a way to reach emergency services.

I propose an expansion of this idea. A special set of numbers, which, like 800 numbers are free to call because the called party pays for the airtime. These exist already of course, but I want to go further and have numbers where any phone, or at least any phone which works with a participating carrier, can call the number, billed to the receiver of the call.

Then people who can't afford a cell phone could still use one, if they liked, to call certain businesses. The first one I'm thinking of are taxis. I've always thought cell-phone hail makes sense for taxis in today's world (and it eliminates the need for a monopoly but one problem was not everybody has a cell phone. Even if the cab companies can't afford the 50 cents they might pay for airtime, it could just be added to the fare, at least in a non monopoly rates world.

This could also enable a cell-phone-hailed jitney service that replaces low-usage transit bus lines. In much of the world, jitneys are popular and cheap. A new high-tech jitney could be much better than the bus, if everybody can get a phone with which to call it.

There are other companies who might participate. Travel companies such as hotels and airlines might allow these calls. Tourists visiting foreign countries might find it useful to reach such companies but they may not want to get a local cell phone or pay giant roaming rates -- or might not have a cell at home that can roam, as CDMA customers realize in the GSM world.

If they could do it in low volume, parents might even participate, allowing their kids to use an old unregistered phone to call them (at high cost) but do nothing else. Of course cell companies might not want to allow this as they may feel they get more money pushing parents to buy phones, or at least prepaid phones, for the kids.

The phones would not be directly callable, but it might be handy if the system allowed the recipients of these target-paid calls to have a temporary number which can be used to call back a caller who has called recently. That's a little more involved. This would be handy for 911 too. And of course, if this became common, more people would have a phone which could call 911 in an emergency. There are tons of old phones out there, and they are cheap.

Companies would have to coordinate. It would be nice if a cell800 customer didn't have to negotiate with every carrier in town, and if they could use the same number on several carriers. Most of these old phones will be subsidy locked and only able to work with one carrier.