Event Calendar & SMS Reminders

I need an event-focused calendar set up that not only lets me schedule occasions quickly but also kicks out automated SMS reminders to every attendee. The goal is to reduce no-shows and give guests a timely heads-up without any manual texting on my end... (Budget: $250 - $750 USD, Jobs: Calendly, Event Management, HTML, JavaScript, PHP, Salesforce.com, Twilio, Zapier)