Transactional SMS
What is a transactional SMS?
A transactional SMS is an automated, non-promotional text message triggered by a user action or system event in an application or website. Unlike promotional texts, these messages don’t attempt to sell products or services. It informs and acknowledges a user action.
Its primary purpose is to convey essential operational information, such as one-time passwords (OTPs), order status updates, delivery tracking, account alerts, appointment reminders, and other user-triggered actions.
Marketing SMS vs. transactional SMS
Here’s a quick comparison table between marketing SMS and transactional SMS.
Feature | Marketing SMS | Transactional SMS |
Primary intent | Sales, promotions, discounts, brand awareness. | Authentication, important updates based on user-triggered actions. |
Trigger mechanism | Scheduled campaigns sent in bulk. | Real-time events or direct user actions. |
Recipient opt-in | Explicit consent is strictly required. | Implicit through transaction or account activity. |
Delivery hours | Restricted by regional regulations. | Delivered instantly and anytime when an action is performed by the user. |
DND exemption | Blocked on Do-Not-Disturb numbers. | Bypasses DND restrictions in most regions. |
Common examples of transactional SMS
Transactional SMS keeps users informed about important actions, updates, and events related to their accounts or transactions. Common examples include:
One-time passwords (OTP)
Verification codes
Account alerts
Payment confirmations and failure
Order confirmations
Shipping and delivery updates
Appointment reminders
Booking confirmations
Account registration messages
Transaction and security alerts
Service notifications
How many characters should a transactional SMS have?
Ideally, a transactional SMS should be less than 160 characters. This limit perfectly fits into a single message segment, decreases extra carrier costs, and delivers messages instantly without any delay.
Standard encodings: Plain text allows up to 160 characters per segment.
Unicode encodings: Messages containing special characters, emojis, or non-Latin scripts (e.g., Hindi, Tamil, and other regional languages) reduce the segment limit to 70 characters.
Concatenation: Messages exceeding these limits are usually split into multi-part segments (each holding 153 characters for standard or 67 for Unicode) and reassembled on the user’s handset.
SMS type | Characters per segment |
Standard | Up to 160 characters |
Unicode | Up to 70 characters |
Multi-segment GSM-7 | Up to 153 characters per segment |