Promotional SMS: this type of message is sent with the objective of promoting a product or service. These messages are sales and marketing SMS’s which may or may not be solicited by the recipient.
Transactional SMS: this type of message is sent to your customers with the purpose of passing on information necessary for using your product or service. For example:
a) SMS sent for two-factor authentication, one-time passwords, etc.
b) Notifications regarding a product or service used by an existing customer, such as an appointment reminder.