As an alternative to the above solutions, if you've ever had SmartThings (and don't mind still using the app), you can also use this community-created Hubitat driver and SmartThings SmartApp together to route notifications to ST from Hubitat: Route Hubitat Notifications to SmartThings (App and Driver)
But in general, as suggested: by using notifications instead of text messages, you won't have to worry about the 10/day SMS limit. 
