Google’s Pixel 4 won’t launch with support for RCS messaging on some of the biggest US networks. Verizon and T-Mobile both said on Twitter that the phone was not supported, as spotted by 9to5Google, and AT&T has yet to say whether it’ll be supported. Only Sprint has said, in an email to The Verge, that it will support RCS, which adds features like read receipts, typing indicators, and higher-quality attachments to the standard Android Messages app.

The rollout of RCS messaging has been a complete mess. The standard, which is supposed to replace the basic SMS and MMS messaging that’s been around for as long as we’ve used smartphones, has been slated to roll out for years now. Its biggest push came in 2018, when Google settled on RCS as the solution for upgrading messaging on Android. But more than a year later, there’s been very little movement. Google said it would start forcing the change on its carrier partners earlier this year, but that hasn’t happened in the US.

Verizon even supported RCS on the Pixel 3, but not here

So with the Pixel 4 about to launch, Google finds its flagship phone missing a feature on many networks that was supposed to be widely deployed by now — and that was even present for some users of its last device.

On Verizon, RCS support was added to the Pixel 3 a couple months after launch. Verizon didn’t support RCS until December of last year, and the Pixel 3 was its inaugural device. The Galaxy S9 later got support, too (though only when messaging within Verizon’s network), but it’s not clear that other phones have been added since.

The Pixel 3 didn’t support RCS on most other major networks, but that was understandable: Verizon was the exclusive carrier partner for the first three Pixel phones. Now that the Pixel 4 is available across all the major US carriers, though, it should be expected that RCS support — something Google has been emphasizing — would be available on its flagship smartphone. Support could be added later if the carriers choose to, but so far, Sprint is the only major name in the US that’s committed to it.

We’ve reached out to AT&T, T-Mobile, Verizon, and Google for more information.

Correction October 18th, 9:00PM ET: This story initially said that the Pixel 3’s RCS support was limited to Verizon, but that was incorrect. Some carriers — such as Sprint and Google Fi — have implemented network-wide universal RCS support. That means earlier Pixels would have be able to use RCS when connected to those networks.

The broader problem here is that the US’s three biggest carriers — Verizon, AT&T, and T-Mobile — don’t yet have network-wide support, which is really the ideal situation so that we’re not asking this question of RCS support phone by phone. For now, Verizon and T-Mobile have been (very occasionally) adding support for devices one by one, such as Verizon did with the Pixel 3.