What we are seeing here is just the start of a trajectory that, I believe, will eventually result in free calling anywhere in the world, anytime.
Softphone services will be first.
Within a couple of years, business models for free calling will offer customers two choices: pay per-minute rates that are similar to today's fee structures or watch ads within the softphone UI, or on the website of the VoIP services provider. Even today's non-softphone VoIP services will introduce softphone products to enable this feature.
Scripts will be written that will enable a viewed ad to launch a special application of the softphone encoded for free dialing. And income from those ads will offset PSTN termination charges.
It's just bits, after all.
And with PSTN termination subsidized, those bits can travel across the street, or across the world.