If you want to send SMS texts and you run out of credits you can still resend them after you purchase additional credits:
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In the resend screen you'll see the option to filter the messages by type: SMS 1- to - 1 Messages, Campaign SMS Messages, and Batch SMS Messages.
You can also filter by date (today, last week, or last two weeks).
There's also the option to search by name, number, or text: 

You can resend the individual SMS by selecting the one you want to resend, you can select multiple contacts as well. Here you'll see more information about the contact as their phone number and the complete text you want to send.
You can resend them immediately or you can also schedule them: 

To resend the campaign you will see the campaign name as well as its description and the option to resend it, once you click on it, you'll be able to schedule the campaign as well: 

For the batch messages, you'll see the batch name, the number of messages that failed the text, and the list of contacts that are part of the batch. You also can send the message right away or to schedule it for another time:  

Remember that you can resend messages that have failed because your location runs out of credit.