DLT registration and the 1600 series, explained for businesses

Which rule applies to you?

What is DLT registration?

DLT (distributed ledger technology) is how operators implement TRAI’s Telecom Commercial Communications Customer Preference Regulations, 2018. 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 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:

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; insurers, our pieces on renewal calls and PIVC.

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 live from 1 November 2026 on 4G and above (see CNAP caller name display), 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 and the call scripts, which include TRAI-aware callback and reminder templates.

How Vocora handles these rules

Vocora’s Voice AI answers your inbound calls and makes callbacks and reminders within the consent rules that apply to your business, and confirms on WhatsApp with approved templates. Outbound calling rules are agreed with you before anything goes live.

Planning automated outbound calls? Our AI telecaller guide maps each call type to the consent and number series it needs, and this guide covers numbers flagged as spam.

To see how these rules apply to plan expiry calls and SMS, read our recharge reminder voicebot guide.

FAQ

Sources

1. PIB — TRAI strengthens consumer protection with amendments to TCCCPR, 2018 (12 February 2025)
2. PIB — TRAI issues directions to curb misuse of messaging services: 140-series migration, whitelisting and traceability (20 August 2024)
3. TRAI Press Release 60/2024 — Whitelisting deadline extended to 1 October 2024 (30 August 2024)
4. TRAI Press Release 90/2024 — Implementation of message traceability for safe SMS service (30 November 2024)
5. Jio TrueConnect — Entity registration and login guide for Principal Entities and Telemarketers
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)
7. PIB — TRAI mandates phase-wise adoption of 1600-series by RBI, SEBI and PFRDA regulated entities (19 November 2025)
8. PIB — TRAI issues Direction mandating 1600-series for IRDAI-regulated entities (17 December 2025)
9. DoT — Allocation of numbering series 1601 to entities in sectors other than BFSI and Government (30 June 2026)
10. TRAI Press Release 113/2026 — Phase-wise implementation of 1601-series for utilities, courier and logistics (10 August 2026)
11. TRAI — Direction on allocation and operationalisation of the 1601 numbering series (10 August 2026)
12. DoT — Circular 01/Licensing Policy/2026: Introduction of calling name presentation service in telecommunication networks (13 October 2026)

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.

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