RCS after iOS: what changed in the numbers, and what to distrust

RCS (Rich Communication Services) is the operator-run upgrade to SMS: branded senders, images, buttons and read receipts inside the phone's default messaging app. Since Apple added it to the iPhone, vendors have quoted ever larger adoption numbers. If you are deciding whether to invest in RCS, you need to know which numbers describe your potential reach and which describe something else. This piece separates what is firmly established from what is loosely counted, and gives a simple way to estimate reach for your own markets. For the basics, start with what RCS changed.

Apple added RCS support in iOS 18, released in September 2024. This is a matter of record, not an estimate.

The GSMA keeps extending the standard. Universal Profile 4.0, published in March 2026, added video calls started from inside a message thread, richer text formatting, and business features such as video inside rich cards and control over how links open. Universal Profile 4.1, published in July 2026, focused on making end-to-end encryption work reliably between different apps, building on encryption work the GSMA had already published.

Together these are the substance: the standard is supported on both major smartphone platforms, and it is still being actively extended. But a specification is not a deployment. New profile features reach people only when messaging apps, phone makers and operators implement them, which typically takes months or years after publication.

Almost every adoption statistic you will meet. Widely repeated figures put the active RCS user base in the billions and describe large multiples in traffic growth since Apple's move.

They may be directionally right. They are also, in most cases, sourced to vendor blog posts that do not define what they are counting. The exceptions worth knowing are Google's own dated figures: more than one billion monthly active users with RCS in Google Messages, reported by March 2024, and more than one billion RCS messages a day in the United States, reported in May 2025. Both count people's messages, not business traffic.

Three questions to ask of any RCS number:

Users or devices? A device that supports RCS is not a person who receives RCS business messages, because operator deployment is a separate condition.

Capable or reachable? Handset support, operator deployment and business-messaging availability are three different gates. A figure counting the first can be several times larger than one counting the third.

Consumer or business traffic? Person-to-person RCS and RCS Business Messaging are different volumes with different economics. Mixing them inflates the number that matters to a business buyer.

None of these is false. Each answers a question next to the one a buyer is asking.

Reach is not one number. It is the product of several, and a buyer's actual reach is decided by the weakest link rather than the headline.

Reach is a market-by-market question, not a platform question. The honest way to size it is to ask your provider for RCS Business Messaging reach in the specific countries and operators you send to. A global percentage averages markets you do not serve. A provider that cannot give per-market figures is quoting a press release.

Design the fallback as a first-class path. Whatever the true reach is, it is not 100%, and the share that receives SMS is not a rounding error. If removing the RCS branch would leave you without a working programme, the architecture is upside down.

Do not compare RCS recipients with SMS recipients. They are different populations. A randomised split within the RCS-capable group is the only comparison that measures the format rather than the audience.

Budget time for verification. Brand verification is per market, can take weeks, and is a prerequisite, not a launch task. It is the same lesson as US 10DLC registration in different clothes; see sender registration around the world.

This is the same pattern as the market-size disagreement: a widely quoted number, a stable underlying trend, and definitions loose enough that the number can be almost anything. The trend is real and worth acting on. The specific figure in the deck in front of you is probably not worth defending.

Handset support is largely solved and is no longer the main constraint. Operator deployment and sender verification are, both are per market, and reach is their product. Design the SMS path as the real one, verify per market on a realistic timeline, and treat any engagement comparison without a control group as a description of who owns a newer phone.

• RCS in an existing SMS programme: how to add RCS without breaking what works.
• GSMA on RCS, encryption and the future of operator messaging: the primary sources, read carefully.