If you send any SMS in India — OTPs, alerts, or promotions — you must be registered on DLT first. It is TRAI-mandated, non-negotiable, and the single most common reason a first SMS send fails. The process has three steps in a strict order: entity → header → template. Here is the complete 2026 walkthrough, with real costs, timelines, and the mistakes that get templates scrubbed.
What DLT is, in one paragraph
DLT (Distributed Ledger Technology) is a blockchain-based registry mandated by TRAI under the TCCCPR 2018 regulation to curb spam. Every business that sends commercial or transactional SMS must register as a Principal Entity with a telecom operator, register the sender names (headers) it will use, and register the exact text of every message (templates). Operators then "scrub" outbound SMS against this registry in real time — anything that doesn't match a registered template is blocked. WhatsApp Business API messages are outside DLT scope; this applies to SMS only.
Step 1 — Entity (Principal Entity) registration
You register once, on any one operator's DLT portal (Jio, Airtel/SmartPing, Vi, or BSNL) — the registration is shared across all operators via the common registry. You'll need:
- Company PAN and GST certificate
- A business email and authorised-signatory details
- Letterhead / incorporation proof
Cost: ~₹5,900 + 18% GST (one-time, Airtel/Jio in 2026) Time: 1–3 working days for approval Result: a Principal Entity ID (PEID) — your permanent DLT identity
The PEID is the ID that follows you everywhere downstream. Register under the legal entity that owns the brand, not a personal account — changing it later is painful.
Step 2 — Header (Sender ID) registration
The header is the 6-character name in the SMS "From" field — likeHDFCBK, SWIGGY, or QCKAUTH. Header type matters:
- Transactional (6-char alpha, starts with a letter). For OTPs and critical alerts. Crucially, transactional headers deliver to DND numbers too — essential for OTP.
- Promotional (numeric). For marketing. Does not reach DND numbers.
Cost: free (after entity approval) Time: 1–2 working days Result: header linked to your PEID and activated
Register every header you intend to use. For OTP you want a transactional alpha header so codes reach DND users — the majority of Indian numbers.
Step 3 — Content template registration
This is where most sends fail. You register the exact body of every message, with variable placeholders for the dynamic parts. Operators scrub live traffic against these templates character by character (outside the variables) — a mismatch is silently dropped.
Template types:
- Service Implicit — OTPs and transaction alerts to users who triggered them. No consent needed.
- Service Explicit — informational messages needing consent.
- Promotional — marketing, DND-filtered.
Cost: free Time: 1–2 working days per template Result: a Template/Content ID used on every send
The variable rules that trip everyone up
- Variables are marked with
{#var#}. A typical OTP template:{#var#} is your OTP for Acme login. Valid for 10 min. - You cannot put a variable at the very start of some operators' templates, and back-to-back variables (
{#var#}{#var#}) are often rejected. - The static text must match exactly at send time — an extra space, a changed word, or a different punctuation mark versus the registered body gets the SMS scrubbed.
- URLs and phone numbers inside the body usually must be pre-declared; arbitrary links get rejected.
Total cost and timeline
Entity registration ~₹5,900 + GST one-time Header registration free 1–2 days Template registration free 1–2 days each ───────────────────────────────────────────────── End to end: ~₹5,900 + GST, roughly 3–7 working days
So the only real cost is the one-time entity fee; the recurring effort is template hygiene. The recurring pain is template rejections and scrubbing mismatches.
The five mistakes that cost the most time
- Registering the entity under the wrong legal name. It must match PAN/GST and the brand. Fixing it means re-doing everything downstream.
- Using a promotional header for OTP. Promotional numeric headers don't reach DND numbers, so OTP delivery silently craters.
- Template text drift. The app sends slightly different copy than what was registered — the #1 cause of "the SMS says delivered in our logs but the user never got it" (it was scrubbed).
- Forgetting to register every variant. Each distinct message body needs its own template; you can't reuse one template for materially different copy.
- Treating DLT as one-and-done. New message types = new templates. Build template registration into your release process.
Do you have to do this yourself?
No. DLT is exactly the kind of compliance plumbing that should be handled for you. QuickAuth takes care of DLT entity registration, sender-ID and template approvals end-to-end — usually within 24 hours, included with onboarding at no extra charge — and keeps your registered templates in sync with what actually gets sent, so you never hit a silent scrubbing failure. If you'd rather skip DLT entirely for verification, WhatsApp OTP is outside DLT scope — see our WhatsApp OTP vs SMS OTP comparison.
Bottom line
DLT is three steps in order — entity, header, template — costing about ₹5,900 once and a few days' wait. The fee is trivial; the ongoing discipline is keeping registered templates exactly in sync with live copy. Get the header type right (transactional alpha for OTP) and treat template registration as part of shipping, and DLT stops being a source of mystery delivery failures.