RCShas been around for more than a decade at this point, first adopted by the GSMA in 2008. It took a long time for the new messaging standard to become widespread, though, withGoogle Messagesplaying a big role. Initially, there were a lot of exceptions, with RCS working on some carriers in some countries only. Those issues were quickly ironed out, but there was still one thing missing: Seamless support for switching between different SIM cards. Google has now added the feature to the Messages beta, and it’s already working for some testers.

As spotted by app expert @AssembleDebug on X (formerly Twitter) and their Telegram channel, a few new strings and flags have surfaced in the latest Google Messages beta. The strings suggest that Google is working on support for dual SIM when using RCS, with a simple switch allowing you to choose which SIM to send messages on the fly. This is similar to how it already works with SMS.

Using the instructions provided by AssembleDebug, another person was able to activate the new SIM switch for RCS messages in the app. Their screenshots show that underneath the regular toggle to turn on RCS, it’s now possible to tick on or off either of two SIM cards they have in their phone. Within an RCS chat, there are also buttons and markers that let you differentiate between the two SIM cards.

In the bottom right corner of the chat box, there is a button that lets you see which SIM card is used to send the message in question. We presume tapping it allows you to quickly change it. Messages themselves are accompanied by a small tag with the name of the carrier, with two different colors making it easier to distinguish them. While the chat with either SIM card lives within a single chat for the sender, it’s not clear if it’s going to be the same for receivers. It likely depends on how they’ve saved their contact’s phone number.

In the past, RCS didn’t work on many dual SIM phones at all, even if they only had one SIM in them. In the course of 2018 and 2019, Google slowly activated RCS on phones with dual SIM support. Even with RCS usable, it wasn’t easy to switch between SIM cards back then, though.

We don’t know just yet when Google is planning to roll out dual SIM support for everyone using the stable release of Messages. Given that the feature is already functional, it may not take a long time, though.