I would guess the FCC allows it now.
The FCC would have to mandate it and force the carriers and content providers to offer it.
There would be much wailing and asking for time and money to make this happen.
The tech is there, but not every carrier/provider has the tech in place like we do.
It would be similar to the FCC mandating Local number portability years ago. This made it possible to move your phone number to a different provider. Cell companies thought this would help them attract costumers if their old landline number could be ported to the cellular company.
It took some time and money, but it happened.