A snippet from my Rakefile which uses Twilio.

Rakefile.rb

#This Rake task fires every 5 minutes, checking for a particular symptom which signals a critical problem.
#If it finds it, it calls Patrick's cell phone.
#This could probably be done with PagerDuty or similar, but since I already had a Twilio account...

desc "Emails sysadmin if reminders are not going out"
  task :check_for_emergency => :environment do
    begin
      had_emergency = Reminder.check_for_emergency!  #Application code checks for a symptom of a critical problem.  
      if (had_emergency)
        twimlet_url = "http://twimlets.com/message?Message%5B0%5D=Appointment%20reminder%20reminders%20in%20processing%20or%20scheduled.%20Appointment%20reminder%20reminders%20in%20processing%20or%20scheduled.%20Appointment%20reminder%20reminders%20in%20processing%20or%20scheduled."
        Twilio::Call.make($TOLL_FREE_NUMBER, $TWILIO_WHITELISTED_JAPAN_CELL_PHONE, twimlet_url)
      end
    rescue Exception => e
      HoptoadNotifier.notify(e)
      raise # to show error in console
    end
  end