SMS fallback is a delivery safety net: when a rich message (such as RCS) can't reach a recipient (because their phone, app or carrier doesn't support it), the system automatically sends a plain SMS version instead, so the customer still gets the essential information.
Why it matters
Not every phone supports RCS, and support varies by device, messaging app, carrier and country. Fallback makes sure that:
- Critical alerts (OTPs, delivery updates, appointments) always arrive
- Campaigns reach everyone, with rich formatting where possible and plain text elsewhere
- You don't need separate campaigns for different phones
How to design for fallback
- Write a short plain-text version of every rich message
- Include the key information and one link
- Keep brand identification clear ("From UrbanThread:")
- Follow local SMS rules; in India, commercial SMS must comply with TRAI's DLT framework
Example
A delivery company sends an RCS card with a map and "Reschedule" button. Customers without RCS receive: "UrbanShip: Your parcel arrives today 2–5 pm. Reschedule: (link)".
RapBooster does not send SMS fallbacks: an RCS message that can't be delivered is not converted to SMS, so keep a WhatsApp or email follow-up ready.
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