Google’s RCS rollout is going..well, it’s going. First, you probably need a refresher on what RCS is. RCS is the carrier supported SMS replacement functionality that Google is pushing. It’ll work like a native version of WhatsApp, allowing typing notifications and read receipts. You’ll be able to send images and gifs, and it’ll all be done over data. Technically, it can be used on any device. With Microsoft’s Windows Phones supporting it in the past and Apple’s iPhones on track to support it.
The RCS roll-out has been slow going so far, and many users don’t even know they have it. Google has added a new feature in version 4.4 of the messages app to let users know whether their devices are provisioned for RCS or not (via Android Police).
That said, not all carriers support RCS worldwide. In the UK, only Vodafone does at this time, making it a not-so-very useful feature for people who aren’t all using the same network. Nevertheless, Google is rolling out this update to users via the Play Store.