Text Message "Not sent. Tap to try Again"

Intermittent issues are the most frustrating because it is sooo hard to pin down the exact cause. The error message "Not sent. Tap to try Again" when sending text messages can be due to several reasons. Here is where I would start:

1. Device Updates and Space: Update your device software to the latest version and ensure your device has at least 15% free space. This is most commonly overlooked, but the main reason why I found messages not working during my time taking tech support calls. I would start with the conversation that you are getting the error message in, but continue by deleting as many text messages, apps, pictures, and files that you can. 
2. Check for Blocks: Ensure that Message Blocking or Family Allowances aren't preventing messaging on your end or the recipient's.
3. Clear Cache and Reset Network Settings: For Android, clear the app cache and data for Messaging. For both Android and Apple devices, reset the Network Settings. 

If the issue persists after these steps, consider moving the SIM card to another T-Mobile device and try texting from that device to determine if it's a network or device issue. If it follows the sim card, you can contact support to have them file a ticket. If it is only on your Motorola phone, you can cycle the phone into Safe Mode to see if it happens when all third-party apps are disabled. If it doesn't happen in safe mode, then you are looking at an app issue and will want to do a master reset. 

It might seem like a lot, but we want to get you back to seamless texting. Hope this helps!