The future of mobile messaging between operating systems is here, it’s just unevenly distributed.

With iOS 18, Apple has made it possible for non-Apple phones to exchange messages with iPhones via Rich Communication Services (RCS). This offers improvements over standard SMS text messaging, such as read receipts, easier and higher quality media sending, typing indicators, and emoji/reply compatibility. Additionally, it allows messaging over Wi-Fi without cellular service and makes navigating and leaving group messages far easier. Notably, RCS messages between iPhones and non-iPhones are not encrypted, like Apple’s private iMessage service, which is exclusively available between Apple devices.

iOS 18 makes these RCS upgrades possible, but not guaranteed, at least at this point. Many people have already enjoyed cross-platform RCS messaging when texting with users of the iOS 18 beta. And iPhones on major carrier plans can now swap RCS with Android users. But some iPhone users, particularly on MVNOs — typically prepaid services that don’t own network hardware but resell access to major carriers — don’t yet have an RCS option available.

Google, a big supporter of Apple’s adoption of RCS, confirmed to Ars that Google Fi, its own MVNO cellular service, does not offer RCS chat for iPhone users over Fi messaging with Android users as of this writing. Android users on Google Fi can use RCS with iPhones from other carriers as long as that iPhone has “RCS interoperability enabled.”

Reading between the lines, one might conclude that Google is waiting for Apple to enable RCS on a network-by-network basis for both Fi and Android users in general. And a Google spokesperson would claim that’s correct.

“We’ve been working to accelerate RCS adoption for a long time, and we’re excited to see Apple taking steps toward RCS adoption with the launch of iOS 18,” a Google spokesperson said in a statement. “Only Apple is able to enable RCS interoperability for iPhone users on Fi, and we hope they will do so in the near future.”

Ars has reached out to Apple, as well as carriers Mint Mobile and Boost Mobile, for comment on RCS availability across carriers and will update this post with new information. Some customers of MVNOs offered by the major carriers themselves, such as those of Verizon’s Visible, have reported having RCS access with iOS 18 installed.

Apple has understood the message and remains green

Users of other MVNOs have asked on Reddit why their upgrade from plain SMS to RCS didn’t happen during the iOS 18 betas. A co-founder and current CFO of Mint Mobile said on September 9 that it will “unfortunately take a few months” as the “backend transition takes some time… Trust me, we want to get this out as soon as possible,” Rizwan Kassim wrote.

A moderator on the Mint Mobile subreddit said the backend change involves carriers setting up a relay API for messages, adding it to the “carrier package” they deliver to customers, and then providing Apple with information that it can incorporate into a future iOS update.

If you have an iPhone that isn’t on one of the major carrier plans (AT&T, T-Mobile, or Verizon) and want to check if RCS should be available, you can do so in Settings. Go to General, select About, and scroll down to the Carrier line under your active SIM or eSIM. Tap the Carrier line until you see IMS Status. If it says Voice and SMS, you don’t have RCS yet, but if it says Voice, SMS, and RCS, you do have RCS.

The version of RCS that iPhone and Android users may be using now or soon is the “RCS Universal Profile,” which does not include the encryption that Google’s own messaging apps provide through RCS. Google’s “Get the Message” campaign attempted to get Apple to adopt RCS. Its associated website notes that “Apple is beginning to leverage #GetTheMessage” with the launch of RCS, but iPhone users will need to “check with their carrier” to enable the feature.

Apple announced RCS support in November 2023. The company’s choice of a particularly bold green color to denote messages that don’t go through its own iMessage servers — but are culturally associated with Android — has inspired both a notable Drake track, a wild month of efforts by messaging startup Beeper to get around its Apple-exclusive nature, and part of the Justice Department’s antitrust lawsuit against Apple. RCS support, whenever it comes for whichever carrier, won’t change the color of cross-platform messages.