The first thing you'll be required to do before you can set-up a receive only SMS campaign is to get a dedicated number.
Once you get your number(s), you'll be able to set up your SMS Campaign.
Sounds obvious, but you need to name your campaign. It might seem trivial for the first couple of campaigns, but after you've sent hundreds, it will be really helpful if you gave your campaigns distinct names that will make it easier for you to track them down or search them.
Usually dates or the topic of the campaign are great hints. Names like "Campaign #1" might not do the trick.
Storing incoming SMS
By default, all replies and inbound SMS will be stored in your SMS Central inbox (Send/Receive >> Inbox).
If you would like to store them someplace else (for example, forward them to a URL or your email), you will need to create some rules & triggers.
Choose your number
The dropdown will show a list of your own pool of dedicated numbers. Select the one you would like to be the recipient of these inbound SMS.
Once you are done, click on CREATE CAMPAIGN, and you are done.