def confirm
    from_phone_number = params['From']
    @registration = Registration.find_by_phone_number(from_phone_number)
    @content = params['Body']

    @twilio_client = Twilio::REST::Client.new(
      TWILIO_SID,
      TWILIO_AUTH
    )

    if @registration && @content == "YES"
      @registration.confirmed = true
      @registration.save

      @twilio_client.account.sms.messages.create(
        :from => TWILIO_NUMBER,
        :to => "+1#{from_phone_number}",
        :body => "Your registration has been confirmed!"
      )
    else
      @twilio_client.account.sms.messages.create(
        :from => TWILIO_NUMBER,
        :to => "+1#{from_phone_number}",
        :body => "Could not confirm your registration."
      )
    end

    render :text => "OK"
  end