--- title: "DLT Registration & 1600/1601 Series Explained" description: "A plain-English guide to TRAI’s DLT registration for business SMS and calls, header suffixes, the 140 and 1600 series, BFSI deadlines and the 1601 series." url: https://vocora.in/blog/dlt-registration-1600-series-explained markdown: https://vocora.in/blog/dlt-registration-1600-series-explained.md last_updated: 2026-10-19 site: Vocora (https://vocora.in) --- [Blog](https://vocora.in/blog) · Rules explained # DLT registration and the 1600 series, explained for businesses DLT is the blockchain-based registry behind TRAI’s rules on commercial communication: any business sending commercial SMS registers itself, its sender headers and its message templates there. The 1600 series is a set of 10-digit numbers that banks, financial firms, insurers and government bodies must use for service and transactional calls. Since August 2026 a separate 1601 series is being rolled out to other sectors, starting with utilities and courier companies. Here is what each rule means for an ordinary business, with the official sources. For how these rules fit an AI receptionist, see the [AI receptionist in India guide](https://vocora.in/blog/ai-receptionist-india-guide). By Vocora team · Published 7 October 2026 · Rules as of 7 October 2026 ## Which rule applies to you? | What you do | What applies | | --- | --- | | Send SMS: OTPs, booking confirmations, alerts, offers | DLT registration of your business, headers and content templates | | Make promotional calls | 140 series, through a telemarketer registered on DLT; never a normal 10-digit number | | Make service or transactional calls as a bank, NBFC, insurer, AMC, broker or pension entity | 1600 series, on TRAI’s deadlines (most passed in early 2026) | | Make service or transactional calls as a utility or courier/logistics company | 1601 series, Phase I from August 2026 | | Answer inbound calls, or call back a customer who just called you | No special series today, but TCCCPR’s consent rules apply to anything commercial | | Message customers on WhatsApp | Not DLT; Meta’s opt-in and template rules (see our [WhatsApp Business API guide](https://vocora.in/blog/whatsapp-business-api-india-guide)) | ## What is DLT registration? [DLT](https://vocora.in/blog/voice-ai-whatsapp-glossary#dlt) (distributed ledger technology) is how operators implement TRAI’s [Telecom Commercial Communications Customer Preference Regulations, 2018](https://vocora.in/blog/voice-ai-whatsapp-glossary#tcccpr). TRAI describes TCCCPR as a blockchain-based regulatory framework for spam control. Four things are recorded on it: - **The Principal Entity (PE):** your business, the sender on whose behalf messages go out. - **Telemarketers (TMs):** the registered companies that deliver your messages, and the chain between you and them. - **Headers:** the sender IDs your SMS show. Since the 2025 amendments, headers carry a suffix: `-P` promotional, `-S` service, `-T` transactional and `-G` government. - **Content templates:** the pre-approved text of each message, with placeholders for the parts that change. ## How does DLT registration work? 1. **Register as a Principal Entity on one operator’s DLT portal.** Jio’s TrueConnect guide, for example, asks for PAN or TAN details, GSTN (or another KYC document if you have no GST registration) and your address. On approval you receive an Entity ID and registration certificate. 2. **Reuse that Entity ID elsewhere.** Jio’s portal has a separate flow for businesses already registered with another operator: you enter the existing Entity ID instead of starting again. 3. **Register headers** in the right category. A single content template cannot be linked to multiple headers. 4. **Register content templates** in the correct category. TRAI said in August 2024 that templates registered under the wrong category would be blacklisted, and repeat offences would lead to a one-month suspension of the sender’s services. 5. **Whitelist links and numbers.** Since 1 October 2024, operators may not deliver messages containing URLs, APKs or OTT links that the sender has not whitelisted. TRAI said the timeline for callback numbers would be fixed separately. 6. **Declare your telemarketer chain.** From 11 December 2024, messages whose PE–TM chain is undefined or doesn’t match the declared chain are rejected. TRAI said more than 27,000 PEs had registered their chains by 30 November 2024. In practice, your SMS provider usually walks you through steps 3 to 6. Keep the login and Entity ID with the business, not with an employee or agency. ## What do the 2025 amendments change for senders? - Promotional messages must include an option to opt out. - After someone opts out, you cannot ask them for consent again for 90 days. - Consent given for an ongoing transaction is valid for only 7 days. - Implied consent for service and transactional communication lasts only for the duration of your contract with the customer. - The use of auto-dialers and robo-calls must be disclosed. - Normal 10-digit numbers cannot be used for telemarketing. - Senders and telemarketers face physical verification, biometric authentication and mobile-number linking at registration, and repeat violators can have all their telecom resources, including PRI and SIP trunks, disconnected for a year. For businesses using an AI voice agent for outbound calls, the disclosure and consent points matter most: the agent should say it is automated, call only people who agreed to hear from you, and respect opt-outs. TRAI also required operators to move 140-series telemarketing calls onto the DLT platform by 30 September 2024. ## What is the 1600 series? The [1600 series](https://vocora.in/blog/voice-ai-whatsapp-glossary#1600-series) is a set of 10-digit numbers that the Department of Telecommunications assigned for service and transactional calls by entities in banking, financial services and insurance (BFSI) and by government organisations. DoT’s allocation letters use the pattern 1600-ABC-XXX, where ABC identifies an operator in a particular service area and XXX gives 1,000 numbers for each. The point is simple: if a “bank” calls from an ordinary mobile number, people should be suspicious. TRAI then set deadlines for regulated entities to move their service calls to 1600 numbers: | Entities | Regulator | Last date | | --- | --- | --- | | Commercial banks (public, private and foreign) | RBI | 1 January 2026 | | Large NBFCs, payments banks and small finance banks | RBI | 1 February 2026 | | Remaining NBFCs, co-operative banks, regional rural banks and smaller entities | RBI | 1 March 2026 | | Mutual funds and asset management companies | SEBI | 15 February 2026 | | Qualified stockbrokers | SEBI | 15 March 2026 | | Other SEBI-registered intermediaries | SEBI | Voluntary for now | | Central recordkeeping agencies and pension fund managers | PFRDA | 15 February 2026 | | Insurers and other IRDAI-regulated entities | IRDAI | 15 February 2026 | Adoption was already under way before the deadlines: TRAI said about 485 entities had taken more than 2,800 numbers by 19 November 2025, and about 570 entities more than 3,000 numbers by 17 December 2025. Lenders using voice AI for reminders should read our [EMI reminder voicebot guide](https://vocora.in/blog/loan-emi-reminder-voicebot); insurers, our pieces on [renewal calls](https://vocora.in/blog/ai-voice-insurance-renewal-calls) and [PIVC](https://vocora.in/blog/pre-issuance-verification-call-voice-ai). ## What is the new 1601 series? On 30 June 2026, DoT allotted a separate series, 1601ABCXXX, exclusively for service and transactional voice calls by entities in sectors other than BFSI and government. TRAI explained that it wanted to keep important financial calls from being mixed with calls from other sectors. Its Direction of 10 August 2026 sets out Phase I: - **Who:** utilities (electricity distribution companies, water utilities, city gas distribution, LPG distribution) and logistics and courier services (courier, express logistics, parcel delivery, freight and logistics companies delivering consignments). - **How:** numbers go directly to verified entities, not to intermediaries or aggregators, and each entity gives an undertaking to use them only for service and transactional calls. Promotional calls from 1601 numbers are not allowed under any circumstances. - **When:** operators must complete onboarding of eligible entities within 90 days of 10 August 2026. - **Next:** TRAI will review Phase I (feedback, number use, complaints) and notify more sectors from time to time. If you run a clinic, a workshop, a school or a shop, there is nothing to apply for yet. It is worth watching, because a recognisable service-call number would help callbacks get answered. ## What should a small business do now? 1. **Check your SMS.** Confirm your Entity ID, headers and templates are in the right categories, every link in a template is whitelisted, and your provider has declared the chain. 2. **Separate promotion from service.** Promotions go through 140-series telemarketing with consent; service messages and calls should never carry offers. 3. **Record consent properly.** Note when and how each customer agreed, honour opt-outs, and follow up on enquiries within the 7-day window. 4. **Say who you are on every call.** DoT’s Circular 01/Licensing Policy/2026 of 13 October 2026 makes [CNAP](https://vocora.in/blog/voice-ai-whatsapp-glossary#cnap) live from 1 November 2026 on 4G and above (see [CNAP caller name display](https://vocora.in/blog/cnap-caller-name-display-india)), so until then, and on older networks, most people will see only your number. 5. **Watch for 1601 news** if your sector is close to Phase I. Inbound calls are simpler: answering your own published number, or forwarding it to an AI receptionist, doesn’t need a special series. See our [call-forwarding guide](https://vocora.in/blog/call-forwarding-ai-receptionist-india) and the [call scripts](https://vocora.in/blog/ai-receptionist-call-scripts), which include TRAI-aware callback and reminder templates. ## How Vocora handles these rules Vocora’s [Voice AI](https://vocora.in/voice-ai) answers your inbound calls and makes callbacks and reminders within the consent rules that apply to your business, and confirms on [WhatsApp](https://vocora.in/whatsapp-ai) with approved templates. Outbound calling rules are agreed with you before anything goes live. Planning automated outbound calls? Our [AI telecaller guide](https://vocora.in/blog/ai-telecaller-india) maps each call type to the consent and number series it needs, and [this guide covers numbers flagged as spam](https://vocora.in/blog/business-number-showing-spam-india). To see how these rules apply to plan expiry calls and SMS, read our [recharge reminder voicebot](https://vocora.in/blog/recharge-reminder-voicebot) guide. ## FAQ ### What is the full form of DLT? Distributed Ledger Technology. In Indian telecom it refers to the blockchain-based registry that operators use under TRAI’s TCCCPR, 2018 to record who sends commercial SMS and calls, with which headers and message templates. ### Do I need DLT registration to send SMS from my business? Yes, for commercial SMS such as OTPs, booking confirmations, alerts and promotions. Your business registers as a Principal Entity, then registers its sender headers and content templates. Most businesses do this with help from their SMS provider. ### Do I need DLT registration for WhatsApp messages? No. DLT covers SMS and voice through telecom operators. WhatsApp Business messages follow Meta’s rules on opt-in and templates. If your system falls back to SMS when WhatsApp fails, those SMS do need DLT registration. ### What is a 1600 series number? A 10-digit number starting 1600 that the Department of Telecommunications set aside for service and transactional calls from banks, financial-services firms, insurers and government bodies, so people can tell a genuine call from a fraudulent one. ### 1600 number kya hota hai? 1600 se shuru hone wala 10-digit number hai jo banks, NBFCs, insurance companies aur sarkari vibhaag service aur transactional calls ke liye use karte hain. Promotional calls 140 series se aati hain. Agar koi “bank” ke naam se normal mobile number se call kare, toh savdhaan rahiye. ### What is the 1601 series? A separate series DoT allotted on 30 June 2026 for service and transactional calls from sectors other than BFSI and government. TRAI’s first phase, announced on 10 August 2026, covers utilities and courier and logistics companies. Other sectors will be added later. ### Can my clinic, shop or coaching centre get a 1601 number now? Not under Phase I, which covers only utilities and courier and logistics entities as of 7 October 2026. TRAI says it will notify more sectors after reviewing the first phase. ### Can I make promotional calls from a normal mobile number? No. TRAI’s 2025 amendments restrict senders from using normal 10-digit numbers for telemarketing; promotional calls use the 140 series through registered telemarketers. ## Sources 1. [PIB — TRAI strengthens consumer protection with amendments to TCCCPR, 2018 (12 February 2025)](https://www.pib.gov.in/PressReleasePage.aspx?PRID=2102413) 2. [PIB — TRAI issues directions to curb misuse of messaging services: 140-series migration, whitelisting and traceability (20 August 2024)](https://www.pib.gov.in/PressReleasePage.aspx?PRID=2046872) 3. [TRAI Press Release 60/2024 — Whitelisting deadline extended to 1 October 2024 (30 August 2024)](https://www.trai.gov.in/sites/default/files/2024-10/PR_No.60of2024.pdf) 4. [TRAI Press Release 90/2024 — Implementation of message traceability for safe SMS service (30 November 2024)](https://www.trai.gov.in/sites/default/files/2024-12/PR_No.90of2024.pdf) 5. [Jio TrueConnect — Entity registration and login guide for Principal Entities and Telemarketers](https://trueconnect.jio.com/assets/Trai_module/SampleFileDownloads/Entity_Registration_and_Login_(PE_and_TM_%29.pdf) 6. [DoT — Allocation of telecommunication identifiers in numbering series 1600 for service and transactional voice calls (letter of 31 January 2025, with corrigendum of 21 January 2026)](https://www.dot.gov.in/static/uploads/2026/02/e28d3972d7afcdf1352a78c52903c5fc.pdf) 7. [PIB — TRAI mandates phase-wise adoption of 1600-series by RBI, SEBI and PFRDA regulated entities (19 November 2025)](https://www.pib.gov.in/PressReleasePage.aspx?PRID=2191647) 8. [PIB — TRAI issues Direction mandating 1600-series for IRDAI-regulated entities (17 December 2025)](https://www.pib.gov.in/PressReleasePage.aspx?PRID=2205350) 9. [DoT — Allocation of numbering series 1601 to entities in sectors other than BFSI and Government (30 June 2026)](https://www.dot.gov.in/static/uploads/2026/06/8ff32b52c48ddcf909ac8c18f02abb22.pdf) 10. [TRAI Press Release 113/2026 — Phase-wise implementation of 1601-series for utilities, courier and logistics (10 August 2026)](https://www.trai.gov.in/sites/default/files/2026-08/PR_No113of2026_1.pdf) 11. [TRAI — Direction on allocation and operationalisation of the 1601 numbering series (10 August 2026)](https://trai.gov.in/sites/default/files/2026-08/Direction_10082026.pdf) 12. [DoT — Circular 01/Licensing Policy/2026: Introduction of calling name presentation service in telecommunication networks (13 October 2026)](https://www.dot.gov.in/static/uploads/2026/10/d86da4092d50f052becd6113de83d37e.pdf) TRAI and DoT update these rules often. Check the latest directions on trai.gov.in and dot.gov.in before relying on a date. This article is general information, not legal advice. [AI receptionist guide](https://vocora.in/blog/ai-receptionist-india-guide) · [Glossary](https://vocora.in/blog/voice-ai-whatsapp-glossary) · [Voice AI](https://vocora.in/voice-ai) · [Demos](https://vocora.in/demos) · [Contact](https://vocora.in/contact) --- Source: https://vocora.in/blog/dlt-registration-1600-series-explained · Site index for AI agents: https://vocora.in/llms.txt · Contact: pratik@vocora.in · +91 98041 82483