RCS Fallback

The Sinch RCS API provides 2 fallback options for RCS, based on a range of configurable conditions.

Simple SMS Fallback

Simple SMS Fallback delivers an SMS message to recipients if fallback conditions are met

Using RCS Fallback

In order to use either of the Sinch fallback options, a Sinch SMS account is required.

You can sign up for a free Sinch account here.

When you sign up, you'll have to verify your email address and phone number. This lets Sinch verify your identity and you'll also be able to use your phone to send and receive test messages.
After you've verified your number, you'll be asked some questions in order to get you started in a way that's relevent to you.
After you finish setting up your account, you'll have access to your dashboard where you can view all of your projects and applications. You can also access your account ID, set up API tokens, get phone numbers, and more.

With your Sinch SMS account set up, fallback must be enabled on your RCS Sender Identity. This process is currently not available through the Sinch Dashboard and will need to be completed by your account manager.

Once fallback is enabled, the SMS payload can be included in the POST to the messages endpoint.

Examples of messages with fallback can be found here.

Fallback conditions

The following conditions can be used when configuring RCS fallback. Details on the usage of fallback conditions can be found in the API Reference.

Condition	Default	Description
rcs_unavailable	enabled	Fallback to SMS when the targeted MSISDN is not reachable by RCS. This will happen immediately after the user agent's capabilities have been established.
capability_unsupported	disabled	NOTE: Not currently enabled. Fallback to SMS if the specific capability needed to deliver the provided message payload is not supported by the receiving MSISDN, example, the device doesn't support media messages.
expire	enabled	Fallback to SMS if the per message provided (See ExpireInfo) or RCS REST API system wide(48h) message expiry happens. This means that a delivered notification wasn't received before the message expired. The RCS message will be revoked before sending the fallback SMS. Revocation is also configurable in the FallbackInfo object.
agent_error	disabled	Fallback to SMS if a fatal agent error occurs with a RCS supplier or within the RCS REST API platform. Enabling SMS fallback on agent error guarantees that an SMS is sent instead of potentially delaying a message because of unexpected issues in the RCS delivery pipeline. Agent errors shouldn't occur as RCS matures, but is useful if delivery using any channel is the priority.