Understanding The Difference Between Transactional SMS And OTP SMS


Did you know that the first text message was sent in 1992? The SMS (Short Message Service) was sent from a computer to a mobile phone over a Vodafone GSM network, and it read “Merry Christmas”. Since then, SMS has grown to be a fully-fledged primary form of communication – not only for commercial use but for personal conversations too.

When it comes to finding the right digital communication for businesses, few considerations come to mind: what value do I get from this communication tool? Who am I able to reach and how will I do it? How does this tool stand in comparison with competing solutions? And how can this tool work alongside my existing platform?

Generally, SMS can be broadly categorized into two:

Transactional SMS
Promotional SMS

Transactional SMS is used for informative purposes; for instance, to notify customers of their order or payment status.

Promotional SMS, on the other hand, are used to push campaign messages; for instance, to notify consumers of available product offers.

But of late, there is another kind of SMS called the OTP SMS.

So what is OTP SMS?

OTP mode service is used to share sensitive information between businesses and their consumers, and also to authenticate user logins and transactions. OTP stands for ‘One Time Password’. A code to be used for authentication is part of OTP content.

Difference between Transactional and OTP messages

On the surface, there is not much difference between Transactional SMS and OTP SMS – they are both used to convey informative messages. Differences come in the form of technicalities.

A transaction SMS is something such as “Dear Jane Doe, your order has already been dispatched, and will reach you within three days.” While an OTP message is something like “Dear John Doe, your OTP code is 12345, use it to verify the impending transaction”.

The following are a few basic differences and technicalities that separate Transactional SMS from OTP SMS.

  1. Validation – Transactional SMS must be validated to ensure correctness in terms of message content and the intended recipient. An OTP SMS is not validated before sending, since it is via the OTP that a user is validated.
  2. High priority routeWhat is SMS priority? OTP over SMS is processed under a high priority route as compared to Transactional SMS; this is because OTPs are extremely time-sensitive (an OTP expires within a short period).
  3. Content- Transactional messages are informative in nature, and a user opts-in to receive them. The messages contain information related to the opted-in company. Content of transactional messages ranges from order placement to delivery; from feedback to referral; from an invitation to offers. OTP content is restricted to a limited set of numeric characters that basically is one step of 2-factor authentication.
  4. Voice Backup – While OTP SMS service comes with a voice backup, Transactional SMS does not. For instance, SendOTP - MSG91 OTP platform - comes with an extra set of guaranteed delivery in form of a voice call backup; so if ever (99.99% it doesn’t) an OTP fails the message is delivered via a voice call at no extra cost.
  5. Minimal response time – You send, we deliver! Compared to a Transactional SMS, processing of OTP takes lesser time. This is because the validation process of a mobile number increases the response time for a transactional SMS whereas an OTP itself is sent to validate the number thus reducing the step.
  6. Server Downtime – In rare cases where we experience server downtime here at MSG91, our algorithms are designed in such a way that they give preference to OTP (we’re not biased; we just don’t like our customer getting stressed so OTP goes first).

At MSG91 we treat them all equal – Transactional, Promotional, OTP and try our level best to never disappoint our customers irrespective of the type of SMS they send. But yes, one thing is certain that your OTP will never fail; come what may!


Like to know more about how our OTP services can help you? Reach out to us for a chat.