I think folks are mixing apples and oranges.
Wireless carriers provide a radio interface to the public switched network (PSN).
With wireline service, the consumer has direct access to the public switched network.
Then, there is VOIP, which is a far better interface to the PSN than wireless.
Wireless has the convenience afforded by it mobile radio feature. Nonetheless, if people try to equate wireless to being directly connected to the PSN, they are mistaken.
The RF spectrum, comparatively speaking, is a limited resource unlike the PSN. I can't imagine opening the RF side of the wireless carrier's network like Carterfone (correctly) opened the ability to use customer provided premise equipment access to the PSN.