[peterdoo]

As far as I understand, full MVNOs buy airtime from the MNOs at a very discounted price. However they have to make a huge investment in the equipment in order to interconnect directly to the mobile network, bypassing the termination of the MNO. The termination is done on their own by the full MVNO or by their technical subcontractor.

So Toggle (Lyca UK) would terminate its calls on the Lyca Swiss Network at the price they agree on, and Lyca Swiss would forward the call to Swisscom Network at airtime price, not at the high Swisscom termination rate. Even if Lyca Swiss would charge the official termination rate to Toggle, that money stays in the "family".