There are a few reasons you may not receive a text, and you'll want to check these areas:
1- Unsubscribed by texting 'stop'. Doing this will prevent you from receiving all sms communications. The solution is to text 'start' to receive sms messages again. This usually happens when testing a campaign and incorrectly texting 'stop' to remove yourself and retest. The proper way to test campaigns is to remove yourself from the subscriber's list.
2- No twilio credits. Check your twilio account and make sure you have credits in your twilio account.
3- Number not selected in campaign. Go to STEP 3 of your campaign and make sure a number is selected for your campaign.
4- Carrier blocks. Some carriers block certain messages. To resolve and ensure your messages are delivered, you'll want to use a toll free number.