# SMS Fallback The iMessage route supports graceful fallback for several failure scenarios. **Possible reasons an outbound iMessage send may fail:** * The subscriber is not capable of receiving iMessages * The subscriber has not opted-in via inbound message to the selected Sender Identity * The Sender Identity has been disabled, blocked, or banned * Our iMessage route is temporarily unavailable If any of these failures occur, Mobile Text Alerts will fall back to SMS to deliver your message. This helps ensure your subscriber receives your message, even if there's an issue delivering via iMessage. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://developers.mobile-text-alerts.com/tutorials/message-sending/send-an-imessage/sms-fallback.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.