> In the US, the person receiving the call / text pays for the airtime to the cell phone.
Except few of us actually do. Most plans are unlimited for calls and texts at least. If there's a limit, it's on data.
> The result is that I do get spam messages
Ah, but I'm in the US and I don't get any spam texts :). I do get some robocalls though. It's not an easy to solve problem.
> make the caller pay for the entire path of the call, all the way to the receiver
I think the complication here is that the source of the calls and texts are not other mobile phones. They're coming onto the network via SIP. The billing mechanism to bill all the way back to the sender might be impossible with the current technologies being used. I can send an email to make a text appear on my phone, and this is a feature I have used occasionally -- how do I bill for that?
> Except few of us actually do. Most plans are unlimited for calls and texts at least. If there's a limit, it's on data.
Whether you pay per-SMS or whether you pay bulk for "unlimited" calls and texts, you're still paying for the path from the tower to your phone. Calling a cell phone in the US is the same price as calling a landline.
In the UK, it's possible to buy a phone that has no outgoing minutes or texts. This is useful because people can still call you. In fact, at some point there was a provider that would pay you a "cut" on every SMS or phone call you received. And calling a mobile phone -- whether you're calling from a landline or another mobile phone -- is more expensive than calling a landline.
Which is almost certainly one of the key problems with implementing such a system in the US: in the UK and Europe, mobile phone numbers look obviously different than landline numbers, so you know ahead of time that the call is going to cost you more. In the US, they look the same, so you'd never know how much you would get charged.
> The billing mechanism to bill all the way back to the sender might be impossible with the current technologies being used
If you call my mobile phone, my mobile operator will be paid for that call one way or another; I'm pretty sure neither they nor any of the companies in between your phone provider and mine are going to give it away for free out of the goodness of their hearts. Which means the charge-back mechanism is already in place; it's just not used in the US.
Except few of us actually do. Most plans are unlimited for calls and texts at least. If there's a limit, it's on data.
> The result is that I do get spam messages
Ah, but I'm in the US and I don't get any spam texts :). I do get some robocalls though. It's not an easy to solve problem.
> make the caller pay for the entire path of the call, all the way to the receiver
I think the complication here is that the source of the calls and texts are not other mobile phones. They're coming onto the network via SIP. The billing mechanism to bill all the way back to the sender might be impossible with the current technologies being used. I can send an email to make a text appear on my phone, and this is a feature I have used occasionally -- how do I bill for that?