Cheapest VSP for a UK mobile on O2

[zforum69]

Hi all,

I am trying to help my sister in choose a more cost effective VSP for calls to a UK mobile (O2 I think +447516xxxxxx). We currently use an Australian provider Welcome to PennyTel who currently charge 0.22875 AUD per minute to any UK mobile. That works out to be 0.108256 GBP on current exchange rates.

I've tried looking at all sorts of providers everywhere and cannot seem find a reasonably competitive rate that would cover the cost for any monthly subscription fees to make it work her while. I get the feeling that Pennytel is as good as it gets.

Just to be absolutely sure about it, what is the absolute cheapest VSP that can terminate onto a UK mobile on the O2 network, even if it means only looking at off-peak rates? At this stage, quality and reliability are not in the equation as I want to see if it stacks up financially first.

All suggestions most welcome.
Z