# SMS fallback

When a contact can't receive RCS, Instasent delivers your message as an SMS instead — automatically. How it triggers, how it's set up, and how it's billed.

**Language:** en
**Audience:** platform
**Translation key:** platform.channels.rcs.sms-fallback
**Search keywords:** sms fallback, rcs fallback to sms, automatic fallback, rcs failed delivery, fallback sender, fallback billing, rcs vs sms analytics, fall back to sms
**Related pages:** /platform/es/channels/rcs/sms-fallback, /platform/en/channels/rcs/availability, /platform/en/channels/rcs/what-is-rcs, /platform/en/channels/rcs/senders-verification, /platform/en/billing/pricing-conditions
**Docs index (every page):** https://docs.instasent.com/llms.txt
**This zone's index:** https://docs.instasent.com/platform/en/llms.txt
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**Other language (es):** https://docs.instasent.com/platform/es/channels/rcs/sms-fallback.md

RCS is the rich, interactive version of your message. **SMS fallback** is the
automatic plan B: when a contact can't receive the RCS, Instasent delivers the
message to them by SMS, so the send isn't lost. You don't do anything on each
send — just leave fallback enabled.

In short: RCS is tried first; if it can't get through, it goes out as SMS; and no
one is left without your message.

## When fallback happens

A message falls back to SMS when RCS can't deliver it. It happens in three cases:
the contact's device or app doesn't support RCS, the operator returns an error, or
the RCS message isn't delivered. In any of them, that contact's message is sent as
an SMS and the original is marked **Fallback**.

The decision is made automatically, one contact at a time: if the contact can receive RCS, it's delivered over RCS; if not, it's delivered over SMS.

```mermaid
flowchart TD
    S{"Can the contact receive RCS?"}
    S -->|Yes| RCS["Delivered over RCS"]
    S -->|No| SMS["Delivered over SMS (Fallback)"]
```

The discarded RCS attempt isn't charged. If the SMS fallback runs, the billing conditions of the SMS sent apply.

## Turning on fallback

The fallback sender is set in two places, and the second one wins for that send.

> **Note**: The **RCS Sender** is really the RCS agent registered with Google; in the panel we call
> it "RCS Sender" to keep it consistent with the other channels.

**On the RCS sender**, its detail sheet has an **SMS fallback sender** field — the SMS
sender used when RCS can't deliver. Setting it here is what makes every campaign built
on that RCS sender start out with the right fallback already chosen.

**When you create the campaign** you pick an **RCS Sender** and, next to it, the **SMS
fallback sender**. It isn't optional: every RCS campaign carries a fallback, so the SMS
sender is needed to create it at all. It comes **pre-filled** — with the sender paired on
the RCS sender if there is one, otherwise with your project's default SMS sender — and you
can change it right there or later, while the campaign is still a draft, from its
**Details**.

If your project has no active SMS sender, you won't be able to create the campaign: add
one first.

**Automations work the same way**: the fallback sender is picked when you create them,
using the same form.

**And you can turn it off for one send.** Fallback is **on by default**: in the **Message**
step, between the RCS message block and the SMS one, the **"If RCS is undeliverable"**
connector has a switch you can **turn off** if you don't want an SMS fallback that time.

By default, the fallback SMS repeats the text of your RCS message, and you can
customize it — keeping in mind the SMS
[length and encoding rules](/platform/en/channels/sms/sms-essentials).

![The campaign message step with the RCS message and its SMS fallback side by side, and a toggle for when RCS is undeliverable](/platform/en/channels/images/sms-fallback--3-composer-fallback.png)
*One message, two channels: the RCS message and its SMS fallback prepared together in the campaign editor, ready for the contacts RCS can't reach.*

## What gets billed

There are three cases, depending on how the send ends:

- **It can't be sent as RCS.** The discarded RCS attempt is **not charged**.
- **The SMS fallback runs.** The SMS sent **is billed** under the SMS channel's
  conditions, **even if it ends with a "Failed" status** (for example, an inactive
  number): what's charged is the SMS that was sent, not its outcome.
- **It can't be sent on any channel** — no RCS, no SMS (for example, a country
  without coverage or without an authorized sender). A send that never went out
  isn't charged.

> **Note**: Because part of an RCS campaign may go out as SMS, your final cost can differ
> from a pure-RCS estimate. Per-channel pricing is in
> [Pricing & conditions](/platform/en/billing/pricing-conditions).

## In your analytics

RCS and its SMS fallback are reported **separately** so you can see how each
performed. In the campaign results, the **Channels** breakdown lists an **RCS**
row and a second **SMS** row tagged as *fallback*, each with its own counts. A
message routed to SMS
carries the **Fallback** status. The header metrics and aggregate campaign stats
already include every channel in the chain.

![Results of an RCS campaign with SMS fallback: messages sent, delivery rate, CTR, conversion, revenue and cost](/platform/en/channels/images/sms-fallback-1.png)
*Campaign results add up the whole chain: the messages delivered over RCS and the ones that fell back to SMS.*

![Per-channel delivery breakdown of a campaign: RCS and SMS fallback counted separately, alongside the per-country split](/platform/en/channels/images/sms-fallback-2-channels.png)
*The channel breakdown separates RCS performance from its SMS fallback, and cross-references it with the per-country split.*

To see how many of your contacts need fallback in the first place, check the RCS
support breakdown in
[Availability & rollout](/platform/en/channels/rcs/availability).

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