@andy, 0.15c./mb is the cross network tariff-wholesale price-(charged between operators, what an one EU network charge another EU network) so no need for negotiation, they just make no profit, they just earn form the cash flow (they receive from customers now they pay the carriers later).
http://www.consilium.europa.eu/uedoc...ans/130511.pdf
@gkeeper vikingmobile is a MVNO (mobile virtual network operator) so same networks as Base-Belgium roaming agreements.
i just tried my new vikingsmobile sim in Greece it works as advertised billing 0.15eur./mb... billing incresement is just per 1kb!!
data works on 2 out of the 3 Greek networks pretty well.
great deal for EU data roaming, i set it now as my 1st choice.