El wrote:
> Volume based charges can not be justified by infrastructure costs. If
> the customer bought his own radio/modm that would cut the up front
> cost by half, but I suspect not the packet charges.

That is true. Intuitively at least, it makes more sense when
infrastructure costs are recovered through the basic access fees
(e.g. monthly).

> Actually, I fail to see the necessity of charging by by volume. The
> radio link is probably semi permanent (comes up if either side has a
> packet) or permanent (both recivers listen all the time for packets
> sent to them). This is ideal to charge on a fixed cost basis.

But there are reasons for volume (or usage) charges. The chief one
being congestion. If the traffic that is being generated can exceed
your bandwidth, then you may want some kind of (time-varying or
market-based) usage prices to control demand, and ensure a reasonable
quality of service.  The congestion can occur at the IP layer (delayed
and dropped packets) or the physical layer (radio interference), but
it's essentially the same problem.

If the radio link is not a bottleneck, then I would think usage prices
are difficult to justify. Even less so if the prices are so high that
they are stifling traffic to some level far below capacity.

> Now what if (legalities aside) my ISP had a huge radio station set up
> and I bought a radio/modem which I connected to my linux box, running
> ppp to the other end hooked into a portmaster?
> I'd not have to pay anything to TelCom. Just the monthly 800$US to the
> ISP.

Well, if there are enough ISPs doing the same thing (and granted that
may be years down the road), the frequency spectrum will have to be
explicitly allocated, and somehow the congestion cost has to be paid.

> Again, I fail to see the inherent need to charge by packet.

Inherently there is at a reason. But in practice, today, I don't
imagine there's much congestion in the airwaves of Africa outside of
the major cities.

How do these HF radio prices compare to cellular phone charges, when
the two are being offered in the same geographic area?