Q: Why don't I receive a tone when someone responds to a text sent from my iphone

Hello Doublegood,

After reviewing your post, it sounds like you are not receiving a sound from the notification. I would recommend that you read this article, it may be able to help the issue.

About Notifications on iPhone, iPad, and iPod touch - Apple Support

iOS apps on iPhone, iPad, and iPod touch have three types of notifications:

 

• Sounds/Vibrate: An audible alert plays.

 

Go to Settings > Notifications 

Thanks for using Apple Support Communities.

Have a nice day,

Mario