Bulk SMS · DLT

Bulk SMS service for India, with DLT built in.

A bulk SMS service provider in India sends high-volume text messages on operator networks under TRAI’s DLT rules, so every sender ID and template must be registered. Slovio sends OTPs, alerts and promotional SMS on your DLT-registered sender IDs and templates, from campaigns, workflows and the API. SMS is send-only, with delivery reports.

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PE ID, headers, templates
Campaigns and API
Delivery log

SMS at a glance

SMS in India: DLT sender IDs and templates.

In India, every business SMS runs on the DLT framework. Slovio checks it before anything is sent.

Direction: Send-only. Replies to SMS are not received in Slovio.
DLT details: Principal Entity ID, sender IDs and content templates.
Validation: Sent only when header and template are both approved.
Sends from: Campaigns, workflow steps and the API.
Destinations: Only the countries your account is permitted to reach.
Reports: Delivery log with status and charge for every message.

Side by side

OTP, transactional or promotional SMS?

Every SMS in India goes out on a DLT template registered for its purpose. The category decides who it can reach and when.

Compare	OTP	Transactional	Promotional
Used for	One-time passwords for sign-in and payments	Order, booking, delivery and account updates	Offers, launches and reminders to buy
Numbers on DND	Delivered	Delivered	Not delivered
Sending hours	Any time	Any time	9 am to 9 pm
Sent from Slovio	The API or a workflow step	Workflows and the API	Scheduled campaigns to a CRM segment

Used for
OTP
One-time passwords for sign-in and payments
Transactional
Order, booking, delivery and account updates
Promotional
Offers, launches and reminders to buy
Numbers on DND
OTP
Delivered
Transactional
Delivered
Promotional
Not delivered
Sending hours
OTP
Any time
Transactional
Any time
Promotional
9 am to 9 pm
Sent from Slovio
OTP
The API or a workflow step
Transactional
Workflows and the API
Promotional
Scheduled campaigns to a CRM segment

Slovio queues an SMS only when its sender ID and template are both approved on DLT for that category.

SMS capabilities in Slovio

OTP, transactional and promotional SMS.

Registration details, sending and reporting in one place, so a message on an unregistered header or template is never queued.

DLT details in one place

Your Principal Entity ID, sender IDs (headers) and content templates, each with its current approval status.

Validated before sending

A message is sent only when both its header and its content template are registered and approved.

SMS campaigns

Choose a sender ID and an approved template, fill in the variables, preview the message and schedule the send.

Delivery log

Search every message by recipient number or sender ID, with its delivery status and the amount charged.

Automation and API

Send SMS from a workflow step, or through the API for OTPs and alerts from your own systems.

Country controls and wallet billing

Messages go only to countries your account is permitted to reach, and each send is charged to your wallet.

How it works

Live on SMS in three steps.

Add your DLT details once, automate the sends, then check every message in the delivery log.

Step 01
Add your DLT details
Enter your Principal Entity ID, sender IDs and content templates, each with its approval status.
- PE ID
- Sender IDs
- Templates
Step 02
Automate the sends
Schedule campaigns to segments, add SMS steps to workflows, or send OTPs and alerts through the API.
- Campaigns
- Automation
- API
Step 03
Measure in reports
Search the delivery log by number or sender ID, and see sent, delivered and failed totals in Analytics.
- Delivery log
- Analytics

Use cases

What businesses send by SMS.

SMS reaches every mobile phone. Slovio keeps each message on a registered, approved template.

Notifications
OTPs and account alerts.
Send one-time passwords and account alerts from your application through the API, on an OTP template.
Support
Order and service updates.
Automation texts the customer on a transactional template when an order ships or a ticket changes status.
Marketing
Promotions to a segment.
Schedule a campaign on an approved promotional template for a CRM segment.
Sales
Reminders that bring customers back.
Payment and appointment reminders sent from the workflows your team already runs.

Part of the platform

SMS is one channel. Slovio runs them all.

What happens on SMS joins the same contact record as every other Slovio channel, so your team sees one history per customer.

All channels

SMS on Slovio: questions and answers

What is DLT registration for bulk SMS?

DLT (Distributed Ledger Technology) is the registration framework for commercial SMS in India. A business registers as a Principal Entity, then registers its sender IDs, known as headers, and its message templates with an operator. Slovio lets you record all three and sends only on approved header and template combinations.

What is the difference between transactional and promotional SMS?

Transactional SMS carries information a customer needs, such as order updates and account alerts, while promotional SMS carries offers and marketing. OTPs are a separate category. In Slovio, each content template is recorded as Transactional, OTP or Promotional, so every campaign and automated message is sent on a template registered for its purpose.

Do I need DLT to send SMS in India?

Yes. Under TRAI’s rules, every business that sends commercial SMS in India must register on an operator’s DLT platform as a Principal Entity, together with its sender IDs and message templates. Operators block messages that do not match a registered header and template. Slovio records your DLT details and refuses to queue any SMS whose header and template are not both approved.

Can customers reply to SMS in Slovio?

No. SMS in Slovio is send-only: it delivers OTPs, alerts and promotions, and replies to those messages are not received in Slovio. For two-way conversations, use a channel such as WhatsApp or RCS, where replies reach the Slovio Team Inbox and can be answered by AI Agents or your team, with the history kept in Slovio CRM.

Can I send OTP SMS through an API?

Yes. You can send one-time passwords and account alerts through the Slovio API or from a workflow step in Slovio Automation. Each message uses a sender ID and an OTP or transactional template registered for that purpose, and every send is recorded in the SMS delivery log with its status and charge.

How do I send a bulk SMS campaign on Slovio?

In Slovio you choose a sender ID and an approved template, fill in the template variables and preview the final message. You then select your audience, such as a CRM segment, and choose whether to send immediately or at a scheduled time. Delivery status for each message appears in the SMS delivery log.

How is SMS billed on Slovio?

Slovio charges each SMS to your account wallet at the time of sending. Rates depend on the destination country, and your account can send only to the countries it is permitted to reach. The delivery log shows the amount charged for every message. See the pricing page, or contact our team for current rates.

Documentation

Learn how it works

All SMS guides →

Connect SMSConnect DLT-registered SMS to Slovio with your Principal Entity ID, what DLT registration you need first, and how to tell whether the channel can send.SMS sender IDs and templatesAdd your DLT sender IDs (headers) and content templates to Slovio, link each template to its senders, and get both approved so your SMS can be sent.SMS delivery logUse the SMS delivery log in Slovio to see every message's status, failure reason, charge and refund, filter by number, sender or status, and export a campaign.

Send SMS that meets DLT rules.

Add your DLT details once, then send campaigns, OTPs and alerts that are validated before they leave.

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Explore before you choose a plan · Usage billed from a prepaid wallet

Bulk SMS service for India, with DLT built in.

SMS in India: DLT sender IDs and templates.

OTP, transactional or promotional SMS?

OTP, transactional and promotional SMS.

DLT details in one place

Validated before sending

SMS campaigns

Delivery log

Automation and API

Country controls and wallet billing

Live on SMS in three steps.

Add your DLT details

Automate the sends

Measure in reports

What businesses send by SMS.

OTPs and account alerts.

Order and service updates.

Promotions to a segment.

Reminders that bring customers back.

SMS is one channel. Slovio runs them all.

All channels

SMS on Slovio: questions and answers

What is DLT registration for bulk SMS?

What is the difference between transactional and promotional SMS?

Do I need DLT to send SMS in India?

Can customers reply to SMS in Slovio?

Can I send OTP SMS through an API?

How do I send a bulk SMS campaign on Slovio?

How is SMS billed on Slovio?

Learn how it works

Send SMS that meets DLT rules.

Bulk SMS service for India, with DLT built in.

SMS in India: DLT sender IDs and templates.

OTP, transactional or promotional SMS?

OTP, transactional and promotional SMS.

DLT details in one place

Validated before sending

SMS campaigns

Delivery log

Automation and API

Country controls and wallet billing

Live on SMS in three steps.

Add your DLT details

Automate the sends

Measure in reports

What businesses send by SMS.

OTPs and account alerts.

Order and service updates.

Promotions to a segment.

Reminders that bring customers back.

SMS is one channel. Slovio runs them all.

All channels

SMS on Slovio: questions and answers

What is DLT registration for bulk SMS?

What is the difference between transactional and promotional SMS?

Do I need DLT to send SMS in India?

Can customers reply to SMS in Slovio?

Can I send OTP SMS through an API?

How do I send a bulk SMS campaign on Slovio?

How is SMS billed on Slovio?

Send SMS that meets DLT rules.