Apart from the fact that we class the ISP's use of 0845/0844 as valid to pay for what is otherwise access to their free services, this has been discussed at some length before.
Even if there were an alternative for it, it wouldn't get you what you're after. The service would have to be wound up as it would be losing money.
There ain't no such thing as a
free lunch
and although it may be called
Free-Dialup.net, it has to be paid for somehow.