Fallback to SMS

What fallback actually does

When a brand sends an RCS message, the platform first checks whether the recipient can receive RCS right now. That capability check goes to the carrier or to Google's RBM infrastructure. If the answer is "yes," the rich message delivers as designed. If the answer is "no" (older device, carrier without RCS, RCS toggled off, currently roaming on a non-supporting network), the platform automatically converts the payload to SMS and delivers that instead.

The brand sends one message. The customer receives the best version their device can render.

Why this design exists

Carriers, platforms, and brands all share the same underlying goal: messages should arrive. The richest possible version is preferred, but a plain version that arrives is always better than a beautiful version that does not. Fallback is the engineering answer to "what if the channel is not available."

How conversion works in practice

A platform handling fallback typically does the following:

• Strip rich elements (cards, carousels, suggested replies) and translate them into a text-only equivalent
• For images, either drop them or attach via MMS where supported
• For action buttons, convert "Call us" or "Open menu" into a URL or phone number embedded in the body
• Track which messages went RCS versus SMS so analytics reflect the real channel mix

What brands should know

A few practical implications:

• Always design the RCS message first, but write the SMS fallback copy with intention. Do not let the platform's auto-conversion be your final word.
• Compliance for the SMS fallback follows SMS rules (10DLC sender, opt-in language). The platform handles the routing but the brand owns the consent.
• Pricing differs. RCS messages cost more than SMS, so a high-fallback list (lots of older devices) will trend toward SMS pricing.
• Reporting should distinguish RCS delivery from SMS delivery, because engagement rates are very different and you want to optimize for both.

The strategic point

Fallback is what makes RCS adoptable today. Brands do not have to wait for 100% RCS coverage to start using it, because every campaign reaches every customer. The richer experience is layered on for those who can receive it, and SMS is the floor for everyone else.