There are two ways in which you can accept replies:
1. SMS Inbox
To receive replies from your SMS campaign, click on the 'Advanced options' heading
Select 'Yes' from he 'Allow patrons to reply to this message' dropdown.
This will place any replies into the 'SMS Inbox' located in the orange menu.
This will also replace the 'From' name with a mobile number to accept the replies.
SMS Inbox is located in the Orange Menu, in the top left corner of the screen. It's the 2nd item from the bottom.
Once in this window, you will be able to reply, view, export and optout the contacts.
Enter your number into the 'From Display' - this will also display that the message has come from you.