T-mobile Group messages are not getting delivered after porting from Tmobile to ATT

Good morning, @Vmohanra. This is not the experience we want you to have. There are a few basic troubleshooting steps we can recommend. However, we will also need more information in order to provide a more tailored solution. 

• Turn your device off. Wait at least 30 seconds to turn it back on. (Waiting 5 minutes is better).
• What type of device do you have? Troubleshooting steps will vary based on if you have an Apple or Android smart phone. However, these are the steps for resetting your network settings on either device type: 
  • Apple devices: Go to your Settings > Choose General, then Transfer or Reset iPhone > Select Reset and Reset Network Settings.
  • Android devices: Go to your Settings > Choose General Management, then Reset > Select Reset Network Settings and then Reset Settings.

Let us know how these steps work for you! If you need additional assistance, please don't hesitate to reach back out. 

Thank you for being a part of AT&T Community and Forums. 

Goodacre, AT&T Coummunity Specialist