Correct. And it took more than a decade to get MMSC interoperability. It's still not perfect even now.
And mobile network operators were incentivized to enable MMSC peering because it was typically a pay-per-message service with hefty fees.
> Annoying, though hardly unexpected at this point. Still, that only poses a problem for Google's RCS servers, not for RCS itself.
That's a distinction without difference in the US.