There are certain things to remember about text message responses and best practices when asking people to respond or not.
Long Number Replies
If you're on a Ten Digit Long Code these are the best for collecting replies from customers. You can have true two-way conversations with any contact.
Shortcode Replies
If you're on a Shared Shortcode, you're not the only customer who uses that number. Your ability to collect replies is very limited and you have the off chance that someone replies with a keyword owned by another customer. When this happens, they will get the auto-response from that keyword - which can cause confusion. If you're doing higher volume sending, and need replies, you should consider getting on your own Dedicated Shortcode.
Best Practices
If you DO want responses - Ask people to reply with YES, NO, Y or N - we reserve those types of responses for everyone to use on shortcodes and it makes it really simple to sort your replies.
If you DO NOT want responses - Be sure your message language limits the possibility of responses. Meaning, don't end your messages with questions or content people will feel inclined to respond to.