Yes, you can! To do that you need an Exophone which supports incoming SMS. Get in touch with your Account Manager (Support widget on the bottom of your dashboard).
Once you have the Exophone:
1) Read this FAQ solution to setup your number.
2) Go to App Bazaar->'Installed Apps' tab and click on 'Create SMS App' button on any existing app that you have
3) Drag and drop the 'Menu' applet in the "When an SMS message is received, what should we do?" section
4) Enter the keywords you want to check for and setup the flow for each keyword (similar to the menu applet in 'Voice applets')