If a non-Shuffle User has your card they can use Chatter.
Make sure that your Chatter feature is activated on your card, to do that see How to add Chatter to your card
Upon selecting the sent link
Your card will open and show the Chatter icon:
This will start the chat screen:
After the person inputs their information then selects "Chat" to start the chat:
After typing inthe message and selecting "Send" you will get a message:
That you can respond: