Chances are you might be using both, in different areas.
In Tanzania they have this popular LUKU which depends on inbuilt algorithms and the other Type for mobile workshops or workshops located somewhere with no permanent buildings.These guys use same powerline as a LAN and loaded directly from Power Suppliers(TANESCO).
There might be another type which I havent yet confirmed that use GSM network.

> On Mon, Apr 23, 2012 at 18:27, Bernard Mwagiru <bmwagiru@gmail.com> wrote:
> By "data" I suppose you meant the prepay voucher numbers.
> No.That data is not transmitted via the power lines to some backend billing system via some "big" LAN.
>
> The vouchers are generated by the backend which are translated by the Prepay meter to some units.
>
> ./bernard