Compared to other countries, Twilio SMS rates in the US aren’t bad - for example, take a look at the Twilio SMS pricing for the UK at $0.04/message or Belgium at $0.10/message. Then take into consideration the people complaining about a limit of 100 messages a day.
$0.10/message * 100/day * 30 days = $300/month for a single user abusing the system! 
Edit:
We’ve added a few more notification providers to the SharpTools.io Rule Engine to ease the transition for International Users who’ve recently lost SMS support from SmartThings.
This brings the list of SharpTools notifications providers to:
- Pushover - send push messages to your phone, tablet, or desktop
- Pushbullet - send push messages to your phone, tablet, or desktop
- SMS (Premium) - send SMS messages to US/Canada (included with Premium)
- Twilio SMS - send SMS messages (including international SMS support)!
- Email - send email messages with ease
- Thing - for example, Sonos, Echo Speaks, etc.
You can find more details on the new Twilio SMS and Pushover notification providers here: