RCS (Rich Communication Services) is the next-generation messaging protocol designed to replace SMS. RCS supports read receipts, typing indicators, high-resolution media, end-to-end encryption (in some implementations), and richer interactive content.
Adoption has been slow but is now broad on Android (Google Messages defaults to RCS on most carriers) and Apple added RCS support to iMessage in iOS 18. As of 2026, RCS is the default messaging path between most modern phones — falling back to SMS only when one party doesn't support it.
For business phone customers, RCS mostly works automatically — if both you and your customer are on RCS-capable phones, your messages benefit from the richer protocol without configuration. Kelir's cellular line participates in RCS the same way personal cellular lines do.