You may be experiencing any of these issues:

• You keep receiving multiple copies of the same SMS message.
• You are able to receive SMS messages, but cannot send.
• Outgoing text messages are stuck in pending.

Many SMS issues are network-related. Contact your carrier for advice on possible network issues.

In rare circumstances, SMS messages can become stuck in a pending state and are unable to be sent. This can be resolved by a system update. Ensure the device software is fully updated, by following these steps:

1. Go to Settings and select System Updates. The exact path will differ depending on your device.
   These are the three typical paths:
   
   Settings > System updates > HTC software update
   Settings > Software update
   Settings > AT&T Software Update
   
   
2. Select HTC Software Update to check for new updates.
   If an update is available, follow the on-screen prompts to download and install the update.
   If no update is found, confirm that the device is on the latest software version by navigating to Settings > About > Software Information.
   If no update is available, it is likely that you are already running on the latest version for your device.
   Check the version number and notify your network provider to see if they can help.

Third-party messaging apps may also cause multiple duplicate SMS messages to be received. Clearing the data cache may resolve the issue. See How to wipe your cache partition.

A factory data reset can resolve some send and receive issues. See How to factory reset a device.