There are quite multiple things you need to look at if your campaign's Immediate Text Message isn't going out. Most likely, all the text messages in all your campaigns won't go out as well.
1. Your SMS Settings is not set up properly.
First and foremost, go to Settings > General Settings > SMS Settings and check if you've already set it up. If you've already copied your Twilio/Txtria SID and Token, make sure that you've selected your number.
2. Your Twilio account is still on TEST/DEMO mode
This is also one of the many reasons why the SMS from the campaigns aren't going out. Test numbers are very limited and won't work expectedly on live scenarios. You need to UPGRADE your Twilio account.
3. Your campaign does not have an Immediate Text Message or it is DISABLED
Sometimes it's funny but it can actually happen. Edit your campaign, go to Step 4 and make sure that:
- Your Immediate SMS is "Enabled". Your campaign won't send the Immediate Message if in the first place, it's not enabled.
- You have an Immediate SMS Message. If your Immediate SMS is enabled but you don't actually have any message inside it, then there's nothing to send in the first place.
4. You ran out of Twilio SMS credits
Although this rarely happens, it can still happen. No SMS credits = no sends.