Sent a transactional SMS with a mistake: what you can undo and how to send the correction

The short answer: an SMS that has gone out cannot be deleted or recalled. What you can undo are the ones still scheduled: through the API they can be cancelled before their time. For the ones already sent, you send a short correction, only to the people who got the mistake, saying what is right, and you fix the source of the error before the next send.

What can still be undone

Message status	What you can do
scheduled	Cancel it with POST /v1/sms/messages/{id}/cancel. If the credits had already been taken, they go back to the balance.
queued or sending	Too late to cancel: the API answers 409 with not_cancellable. Get the correction ready.
sent	It has gone to the mobile operator. Only a correction is left.
failed	It did not go out. Fix the text or the number before sending again.

How to write the correction

1	Start with «Correction:», so the customer links it straight to the earlier message.

2	Give only what is right, with the same reference as the first one: the order, invoice or booking number.

3	Apologise once, briefly. Long explanations use up parts and help nobody.

4	If the mistake changes what the customer must do (pay, turn up, collect), say so clearly and give a contact.

Mistake	Correction
Wrong amount	Correction: invoice FT 2026/118 is 1,250 USD, not 1,520. Sorry for the mistake.
Wrong time	Correction: your appointment on 20/11 is at 10:30, not 13:00. Sorry for the mistake.
Sent to the wrong person	Sorry: you received an SMS by mistake that was not meant for you. Please ignore it.

Did the message carry someone else's details? If the mistake sent one customer's data to another, a correction is not enough: tell the affected customer, keep a record of what happened and review your system before sending again.

Finding out who got the mistake

In API answers the number comes masked, so the list of recipients lives in your own system: that is where you keep each SMS id with the order or customer. With that list, send the correction only to those people. A correction sent to every customer causes more confusion than the mistake did.

So it does not happen again

1	Test your texts in the Sandbox with realistic sample data: test cases in the Sandbox.

2	Use templates with blanks to fill. In the SMS Center, a template with an unfilled part in square brackets, such as [DATE], cannot be sent.

3	Check where the data comes from: the mistake is nearly always the wrong field in the database, not the SMS.

Want fewer mistakes, and easy corrections, in your notices? See Transactional SMS.

See Transactional SMS

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