Follow the given procedure to resend failed messages:

1. Under SMS History object, check the Sent Status field for the SMS. — If the sent status of the SMS displays Failed, select all such failed SMS from the list view.
2. Click Resend SMS list button to resend these SMS.
3. If SMS delivery fails due to insufficient SMS credits, customers can recharge their SMS-Magic account and raise a case to resend failed SMS. Our Customer Success team can help you in the process if you provide them with the following details – The preferred date range for sending the SMS — Your account ID.