There are two types of routes. Promotional or Transactional. You must have to choose a route to send a message.
What is Transactional route?
Transactional routes are used to send OTP or reminder SMS. You can send SMS anytime with this route. You cannot use this route to market or promote. You can send SMS both DND/non DND numbers with this route.
What is Promotional route?
Promotional routes are used to send marketing or promotion SMS. You can only send SMS between 9 am to 9 pm. With Promotional route you cannot send SMS to DND activated numbers.