> ## Documentation Index > Fetch the complete documentation index at: https://www.vobiz.ai/docs/llms.txt > Use this file to discover all available pages before exploring further. # Bulk Message Sending: What Is Bulk SMS in India? > Bulk SMS sends one message to many people at once. Learn how bulk message sending works in India: DLT, consent, sending hours, segments and go-live checks. *November 3, 2026 · By [Piyush Sahoo](https://www.linkedin.com/in/piyush-s713/)* Bulk message sending means delivering one message, usually personalised, to a large list of people from a single platform instead of phone by phone. Bulk SMS is its most common form. In India, each commercial batch needs a registered sender and template, and promotional messages face consent and timing limits. This guide is for business owners and marketers planning a first send. It helps you classify your message, get registered, predict how many segments you will pay for, and work out whether your batch finishes inside the permitted hours. Rules link to the regulator's own text wherever we could read it. > [!NOTE] > > **Key takeaways** > > * **Purpose, not volume, decides your rules.** TRAI sorts commercial SMS into promotional, service, transactional and government messages, and each behaves differently. > * **Register before you launch.** Your business, sender name and template wording must exist on a DLT portal, or operators reject the message. > * **One line of offer changes everything.** An order update with a discount in it counts as a promotional message. > * **Promotional sends have a clock.** Plan for 10 am to 9 pm IST, and check that your batch can finish in time. > * **Hindi costs more segments.** A 150-character message is one segment in English and three in Hindi. ## What counts as bulk message sending? In everyday use, bulk sending means one message going to hundreds or millions of people. A bulk SMS platform takes your list, fills in details such as a name or due date, and passes each message to mobile operators. TRAI's definition starts far lower than most people expect. Its [consolidated commercial communication regulations](https://www.trai.gov.in/sites/default/files/2026-05/CA_21052026.pdf) call messages on a similar subject "bulk" once they exceed 20 in 24 hours, 100 in seven days, or 300 in 30 days. Businesses usually send in two patterns: * **Batch sends.** You choose a list and a time, such as a festival offer or a notice about changed branch hours. * **Triggered sends.** Your systems send one message when something happens, such as a login code or a dispatch alert. Both follow the same registration rules. The difference matters for planning, because only a batch needs a list, a schedule and a finish time. ## Which type of message are you sending? Answer this first, because the type decides your sender name, your consent needs and your sending hours. Many guides describe two types, promotional and transactional. TRAI's text goes further. [Its 2025 amendment](https://www.trai.gov.in/sites/default/files/2025-02/Regulation_12022025.pdf) defines service and transactional messages separately and adds a government category. ![Decision map for classifying a bulk SMS. Any offer or advert makes it promotional. A response within thirty minutes of a customer-started transaction is transactional. Product or delivery information for an existing customer is service. A message helping complete a purchase under seven-day explicit consent is also service. Anything else needs consent or goes as promotional.](https://mintcdn.com/vobizai/mqmO5fv1DjIYZtT2/images/blog/what-is-bulk-sms/message-type-map-light.svg?fit=max\&auto=format\&n=mqmO5fv1DjIYZtT2\&q=85\&s=ef41857a457d4a9a0244896535d350bc) | | Promotional | Service | Transactional | | - | - | - | - | | **Everyday examples** | Sale announcement, new product launch | Delivery update, warranty notice, balance alert, login OTP | Payment OTP, payment confirmation, refund notice | | **Sender name ends in** | `-P` | `-S` | `-T` | | **Consent** | Goes to people who haven't blocked it, or who gave explicit digital consent | Not needed for existing customers. Explicit consent, lasting seven days, for a purchase in progress | Not needed, but it must respond to a customer action within 30 minutes | | **Time bands** | Applies | [Not blocked](https://www.trai.gov.in/sites/default/files/2026-09/Regulation_18092026.pdf) | Not blocked | Three rules catch people out: * **Mixed messages become promotional.** TRAI treats a transactional or service message with promotional content as promotional. "Your order has shipped, and here's 20% off your next one" must follow the promotional rules. * **Old consent expires.** Consent implied by a customer relationship lasts [only as long as the contract](https://www.trai.gov.in/sites/default/files/2025-02/PR_No.11of2025.pdf). After someone opts out, you must wait 90 days before asking them again. * **Login codes are moving.** [TRAI's 2026 amendment](https://www.trai.gov.in/sites/default/files/2026-09/Regulation_18092026.pdf) classes OTPs for app login, password reset and two-factor authentication as service messages. OTPs tied to a transaction stay transactional. ## What do you need before your first send in India? Plan your registration before you compare providers. The order below runs from your business to your wording. The first four steps match [Vobiz's DLT registration guide](https://www.vobiz.ai/docs/best-practices/dlt-registration.md). **1. Register your business** Register as a Principal Entity on a DLT portal. Keep your business documents ready, such as PAN and GST details. You receive an entity ID that identifies you to every operator. **2. Register a sender name** This is the header people see instead of a phone number. Register it for the right message type. A header that goes [unused for 90 days](https://www.trai.gov.in/sites/default/files/2025-02/Regulation_12022025.pdf) is deactivated until you ask for it back. **3. Register each template** A template fixes your wording and marks the parts that change, shown as `{#var#}`. [TRAI's rules](https://www.trai.gov.in/sites/default/files/2025-02/Regulation_12022025.pdf) allow more than three variables only with justification, and at least 30% of such a template must be fixed text. One template can link to only one header. **4. Register consent wording for promotions** Promotional senders also [need an approved consent template](https://www.vobiz.ai/docs/best-practices/dlt-registration.md), which sets the wording used to ask for permission. **5. Whitelist your links** Messages with web links, app links or callback numbers go through [scrubbing against the list you upload](https://www.trai.gov.in/sites/default/files/2025-02/Regulation_12022025.pdf). You also sign an undertaking that those links are safe. **6. Give the IDs to your provider** Each send carries your entity, header and template IDs. Vobiz's [India DLT guide](https://www.vobiz.ai/docs/sms/compliance/india-dlt.md) explains what each one means. Copy your message text from the registered template instead of retyping it. [Vobiz's India DLT guide](https://www.vobiz.ai/docs/sms/compliance/india-dlt.md) names drift between the two as the most common reason an Indian operator rejects a message. ## What checks does each message face? Think of DLT as a set of filters run by operators. Some problems stop your entire batch, while others remove only certain people. ![Flow of five checks between a sender's list and a phone: registered header, matching template, whitelisted links, preference or consent, and time band and day. Checks one to three can stop a whole batch. Checks four and five filter person by person. Messages that pass arrive with a type suffix on the sender name.](https://mintcdn.com/vobizai/mqmO5fv1DjIYZtT2/images/blog/what-is-bulk-sms/five-checks-light.svg?fit=max\&auto=format\&n=mqmO5fv1DjIYZtT2\&q=85\&s=d81d484b7fbd63d6bdb23b20f7e9ef4f) The order above is ours, for clarity. TRAI doesn't publish it as a sequence, but its [scrubbing rules](https://www.trai.gov.in/sites/default/files/2026-05/CA_21052026.pdf) do set out checks four and five. A person's explicit consent overrides the content categories they have blocked. The time band and day check is listed separately, so don't assume consent lifts it. People can block by category too. [TRAI's list](https://www.trai.gov.in/sites/default/files/2025-02/Regulation_12022025.pdf) includes banking, real estate, education, health and more, so a person may accept consumer goods offers and still refuse property ads. This is why your delivered count can fall well below your list size without any fault in your message. ## When can you send promotional SMS? Plan for **10 am to 9 pm IST**. TRAI's [schedule of time bands](https://www.trai.gov.in/sites/default/files/2026-05/CA_21052026.pdf) keeps the bands before 10:00 and after 21:00 off by default for every customer who hasn't chosen otherwise. ![Twenty-four hour timeline for India. Promotional SMS is open by default from 10:00 to 21:00 IST and off by default from midnight to 10:00 and from 21:00 to midnight. Transactional and service messages are not blocked in any time band.](https://mintcdn.com/vobizai/mqmO5fv1DjIYZtT2/images/blog/what-is-bulk-sms/sending-hours-light.svg?fit=max\&auto=format\&n=mqmO5fv1DjIYZtT2\&q=85\&s=8e7f60f998cd9e1a189d0d2ee183efb1) You will see other windows online. One Indian guide says 9 am to 9 pm, while another says 10 am to 9 pm. TRAI's band table supports the later start, so 10 am is the safer plan. Ask your provider how late messages are handled before you schedule close to either edge. ### Will your batch finish in time? A large batch sent at a modest speed can run past 9 pm, and a late start makes it worse. Divide your list by your sending rate to find the time you need. | Recipients | At 5 messages a second | At 20 messages a second | At 50 messages a second | | - | - | - | - | | 10,000 | 33 minutes | 8 minutes | 3 minutes | | 100,000 | 5 hours 33 minutes | 1 hour 23 minutes | 33 minutes | | 500,000 | 27 hours 47 minutes | 6 hours 57 minutes | 2 hours 47 minutes | *Our own arithmetic, for planning. It ignores queues and retries, so add a margin.* The promotional window is 11 hours long. At 5 messages a second, that's room for about 198,000 people. For a larger list, raise the rate or split the list across days. ## How much will a bulk send cost in segments? Providers bill per segment, not per message, so length and language both change your total. This guide doesn't quote rates, because they vary by provider and route. Segment counts are what you can control. ![Step chart of billed segments against message length. Plain English text stays at one segment up to 160 characters, then adds a segment every 153 characters. Hindi or other UCS-2 text stays at one segment up to 70 characters, then adds a segment every 67 characters. At 150 characters, English is one segment and Hindi is three.](https://mintcdn.com/vobizai/mqmO5fv1DjIYZtT2/images/blog/what-is-bulk-sms/segments-by-length-light.svg?fit=max\&auto=format\&n=mqmO5fv1DjIYZtT2\&q=85\&s=61f4d83a844786fb71565d6d058aedd0) [The limits](https://www.vobiz.ai/docs/sms/channels/sms.md) depend on the characters you use. Plain English fits 160 characters in one segment. A long plain-English message splits into 153-character parts. Any character outside that basic alphabet, including an emoji or a curly apostrophe, switches the whole message to 70 characters, or 67 per part. Here's what that means for an illustrative send to 100,000 people: | Message | Segments each | Total segments | | - | - | - | | 150 characters of plain English | 1 | 100,000 | | The same 150 characters with one emoji | 3 | 300,000 | | 150 characters of Hindi | 3 | 300,000 | Regional language messages are often worth that cost, but budget for them deliberately. Remember that variables change length too. A long name can push a message into another segment, so test with your longest real values. ## Is your send ready? A go-live check Run through this table the day before launch. | Check | Why it matters | | - | - | | Is the message type right? | [TRAI's 2026 amendment](https://www.trai.gov.in/sites/default/files/2026-09/Regulation_18092026.pdf) penalises templates registered in the wrong category. [See when that starts](#when-the-2026-changes-apply). | | Does the final text match the template? | Operators [reject text](https://www.vobiz.ai/docs/sms/compliance/india-dlt.md) that doesn't match a template under that header. | | Is every link whitelisted? | Links outside your uploaded list fail scrubbing. | | Can you show permission for this list? | A purchased list is a complaint risk. [Keep the date, channel and wording](https://www.vobiz.ai/docs/compliance/india/ucc.md) of each consent. | | Have opt-outs been removed? | People who've left must stay off the list, and you can't ask them again for 90 days. | | Are the numbers in the right format? | Consistent [E.164 formatting](https://www.vobiz.ai/docs/blogs/what-is-e164-phone-number-formatting.md) avoids failed rows and duplicates. | | Have you sent a test to your own phone? | You'll catch broken variables and odd line breaks before everyone else sees them. | | Will the batch finish before 9 pm? | Use the rate table above, and schedule early enough to leave a margin. | > [!WARNING] > > A launched send contacts real people and costs real money. Use your own credentials, check the list, and get sign-off from whoever owns the message. ## Should you use bulk SMS, WhatsApp or RCS? "Bulk message sending" doesn't only mean SMS. Choose by what the message must do and what your audience's phones can receive. | | Bulk SMS | WhatsApp campaign | RCS | | - | - | - | - | | **Best for** | Urgent alerts and offers to the widest list | Rich offers and conversations with people on WhatsApp | Branded messages with tappable buttons | | **What the recipient needs** | Any mobile phone | The WhatsApp app | An RCS-enabled phone, such as an Android handset with RCS turned on | | **What you set up first** | DLT entity, header and template | [Meta-approved templates](https://www.vobiz.ai/docs/whatsapp/api/campaigns.md) | [An approved RCS sender](https://www.vobiz.ai/docs/sms/channels/rcs.md) | | **Reply handling** | Replies depend on the sender type | Two-way conversations | Button taps come back as inbound messages | As a simple rule, use SMS when reach matters most, and WhatsApp when the message needs images, buttons or a conversation. RCS also lets you fall back to SMS for people who can't receive it. ## What happens if you break the rules? People can report spam [within seven days](https://www.trai.gov.in/sites/default/files/2025-02/PR_No.11of2025.pdf) of receiving it. What happens next depends on whether you send through the registered system. ### If you're a registered sender * **Complaint check.** The operator [examines whether the required pre-checks ran](https://www.trai.gov.in/sites/default/files/2025-02/Regulation_12022025.pdf). If they did and delivery followed the rules, it closes the complaint. If not, it acts against whoever is at fault. * **Blacklisted header.** [Your traffic stops](https://www.trai.gov.in/sites/default/files/2025-02/Regulation_12022025.pdf) until your headers and templates are reviewed, or for up to seven days. Repeat violations blacklist you across all operators for at least one year. * **Header or template misuse.** Under [TRAI's September 2026 amendment](https://www.trai.gov.in/sites/default/files/2026-09/PR_No119of2026.pdf), the operator must suspend a misused header or template within six hours of noticing it. * **Wrong category.** Under the [same amendment](https://www.trai.gov.in/sites/default/files/2026-09/Regulation_18092026.pdf), a complaint can get a wrongly categorised template blacklisted. Five blacklisted in 90 days suspends your services for at least a month. ### If you send without registering * **Complaint threshold.** [Complaints from five different people in 10 days](https://www.trai.gov.in/sites/default/files/2025-02/Regulation_12022025.pdf) suspend outgoing services and start an investigation. The 2026 amendment lowers this to three when an operator's AI system has also flagged the sender. * **First violation.** Outgoing services on all the sender's telecom resources are barred for 15 days. * **Repeat violation.** All those resources, including phone lines and SIP trunks, are disconnected across operators for one year, and the sender is blacklisted. ### When the 2026 changes apply The Third Amendment is dated 18 September 2026, and its provisions [take effect 30, 60 or 90 days](https://www.trai.gov.in/sites/default/files/2026-09/Regulation_18092026.pdf) after gazette publication. That puts the six-hour misuse rule no earlier than mid-November 2026. The wrong-category rule and the three-complaint test start no earlier than mid-December 2026. Check current status with your provider or legal adviser. This guide isn't legal advice. A bar on an unregistered sender covers all its telecom resources, voice lines included. That's the strongest business reason to register first and keep every bulk send inside the registered system. ## What should you ask a bulk SMS provider? Ask questions you can verify, and prefer answers you can see in a demo or in the provider's documentation. * Can I set my DLT IDs once for a whole batch? * Can I preview the rendered message and its segment count before launch? * Can I control the sending rate, and pause or cancel a running send? * Does each send check my opt-out list automatically? * Can I export the outcome for each recipient? You'll often see SMS open rates above 90% described as widely reported. We didn't find a regulator or audited source for that figure, so judge success on your own replies, clicks and sales. ## How Vobiz handles bulk SMS Vobiz runs bulk SMS through [broadcasts](https://www.vobiz.ai/docs/sms/broadcasts.md), available in the console under **SMS & RCS → Broadcasts** and through the [Messaging API](https://www.vobiz.ai/docs/sms/overview.md). * **Lists.** You upload a CSV, XLSX or JSON list. Extra columns become personalisation fields, and duplicate numbers are dropped. * **DLT.** You [set your entity, header and template IDs](https://www.vobiz.ai/docs/sms/compliance/india-dlt.md) on the broadcast, and every recipient's message carries them. Once your header is registered, contact Vobiz support to enable it as your sender. * **Preview.** You see rendered samples, the segment count and encoding, and any variables your file is missing. * **Control.** You send now or at a set time, choose a rate from 1 to 50 messages a second, and pause, resume or cancel the run. * **Opt-outs.** Vobiz [checks every send against your opt-out list](https://www.vobiz.ai/docs/sms/opt-outs.md) before it leaves the platform, and records STOP replies automatically. * **Results.** You follow live counts and export a CSV of what happened to each recipient. For other countries, the [compliance overview](https://www.vobiz.ai/docs/sms/compliance/overview.md) covers registration paths such as US 10DLC and toll-free verification. ## Frequently asked questions > [accordion] What is bulk SMS in simple words? > > Bulk SMS means sending one text, often personalised, to many people at once from a business platform. You upload a list, write the message, and the platform hands it to mobile operators. In India, you also need a registered sender name and an approved message template. > [accordion] How can I send bulk messages? > > Register your business, sender name and message template on a DLT portal. Then give those IDs to your messaging provider, upload a list of people who may receive the message, preview the result, and schedule it. Check the delivery report afterwards and remove anyone who opted out. > [accordion] Can I send bulk SMS without DLT registration in India? > > Not for commercial messages. Indian operators check each commercial SMS against the registered sender and template, and they reject messages with no DLT data. Register first. Service alerts and OTPs need registration too. > [accordion] What time can promotional SMS be sent in India? > > Plan for 10 am to 9 pm IST. TRAI's schedule keeps the time bands before 10:00 and after 21:00 off by default unless the customer switches them on. People can also block bands and days inside that window. Transactional and service messages are not limited by time bands. > [accordion] What is the difference between promotional and transactional SMS? > > A promotional SMS advertises something. A transactional SMS responds to something the customer just did, such as a payment OTP, and goes out within 30 minutes. A third type, service SMS, covers updates like delivery notices. One line of offer turns any of them into a promotional message. > [accordion] How many characters can one bulk SMS have? > > One segment holds 160 characters of plain English or 70 characters of Hindi, other non-Latin scripts, or text with emoji. Longer messages split into parts of 153 or 67 characters. You pay for each part, so a short Hindi message can cost three times its English version. ## Further reading on Vobiz * [Vobiz broadcasts guide](https://www.vobiz.ai/docs/sms/broadcasts.md) · [Sending SMS: segments and statuses](https://www.vobiz.ai/docs/sms/channels/sms.md) · [Opt-outs](https://www.vobiz.ai/docs/sms/opt-outs.md) * [India DLT identifiers](https://www.vobiz.ai/docs/sms/compliance/india-dlt.md) · [DLT entity registration](https://www.vobiz.ai/docs/best-practices/dlt-registration.md) · [UCC and NDNC compliance](https://www.vobiz.ai/docs/compliance/india/ucc.md) * [SMS quickstart](https://www.vobiz.ai/docs/sms/quickstart.md) · [WhatsApp campaigns](https://www.vobiz.ai/docs/whatsapp/api/campaigns.md) ## Sources **Indian regulator** * TRAI, [Telecom Commercial Communications Customer Preference Regulations, 2018, consolidated text](https://www.trai.gov.in/sites/default/files/2026-05/CA_21052026.pdf), published May 2026. * TRAI, [Second Amendment Regulations, 2025](https://www.trai.gov.in/sites/default/files/2025-02/Regulation_12022025.pdf), 12 February 2025. * TRAI, [Press release 11/2025 on the amendments](https://www.trai.gov.in/sites/default/files/2025-02/PR_No.11of2025.pdf), 12 February 2025. * TRAI, [Third Amendment Regulations, 2026](https://www.trai.gov.in/sites/default/files/2026-09/Regulation_18092026.pdf), 18 September 2026. * TRAI, [Press release on the Third Amendment](https://www.trai.gov.in/sites/default/files/2026-09/PR_No119of2026.pdf), 18 September 2026. **Industry pages (read November 3, 2026)** > [card] [Send your first SMS on Vobiz](https://www.vobiz.ai/docs/sms/quickstart.md) > > Set up messaging and test a send with your own credentials. 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