Transactional SMS are those SMS wherein overall text format of SMS remains same except the variable information passed in. In India SMS traffic is divided into majorly two categories, Promotional SMS & Transactional SMS. It falls under A2P category.
Transactional SMS are in general intended to pass on necessary information to all those who are part of the transaction or known people/group.
SMS from Banks, Airlines, Ticket Booking, Insurance SMS, SMS from Hospitals or Health Organizations, Alert Messages, SMS from Educational Institutes to parents / guardians, e-commerce SMS, Stock SMS related to Buy/Sell transactions, Information to employees via SMS, Updates to customers, Participation Confirmation by Event Organizations, SMS integration with Inquiry form on Websites.
You get six character Sender ID, so as you can send SMS by your company/product brand. Transactional SMS are delivered to all those even registered in DND (Do Not Disturb) & can be sent 24/7.
Marketing content is strictly prohibited using Transactional SMS Route.