Rich Communication Services (RCS) are the successor to SMS texting, and it was first rolled out late last year for the Google Pixel 3 and the Pixel 3 XL on Verizon. With RCS, you can send messages as long as 8,000 characters, 50 times the 160 character cap on SMS. You'll know if a message that you sent someone has been read, and with RCS you can tell when someone is tapping out a message to you. RCS also allows up to 100 participants to chat at the same time, and messages can be sent and received over Wi-Fi.
TmoNews reports that RCS support is part of an update being sent out now to T-Mobile subscribers who own the OnePlus 6T. The update weighs in at 148.3MB and also includes the January Android security patch. The fact that the phone isn't receiving the March, or even the February security patch is surprising for OnePlus; the company has otherwise pushed out updates from Google in a timely fashion.Today,
The update has not yet hit T-Mobile's software support web page for the OnePlus 6T, and if you have yet to receive it, you can coax it out of your phone manually by going to System > System update > Check for update. One last interesting little note. Those with the carrier locked version of the phone are receiving the update before those with the unlocked variant of the OnePlus 6T.