If a message cannot be delivered to a handset it is a good idea expire the attempt so that the message does not get delivered late at night. Depending on the carrier, undeliverable messages are set to retry based on different timings which can lead to messages being delivered at undesirable times.
1. Click on SEND SMS
2. Scroll down to the 'Pending Message Expiry' and select YES from the drop down list
3. From the drop down list select in how many hours you would like the message with the 'Pending' status to stop trying to be sent.
4. Click on the NEXT button to proceed to the confirm your SMS campaign screen