Block Spam Calls and SMS in India: DND to Chakshu

Quick answer

Sign up for DND on 1909 (a toll-free call) or in the TRAI DND app. It won’t touch OTPs or other transactional SMS. Next, enable the spam filter built into your phone. Sales calls or texts still getting past? Lodge a complaint within 7 days through 1909, your operator’s own app or the TRAI DND app. Scam attempts belong on Chakshu, part of Sanchar Saathi. Lost money already? Ring 1930.

Spam has no single off switch. Think of it in layers instead: DND covers registered telemarketers and nobody else, network and handset filters label much of the leftover, complaints get rule-breakers punished, and Chakshu deals with people out to cheat you.

So work out what kind of call or message you’re getting first. The table below points you to the right fix.

In this article10 topics

Start here: match the problem to the fix
Read the number or header before you answer
Fix 1: Register on DND
Fix 2: Complain about senders who break the rules
Fix 3: Use your operator’s spam warnings
Fix 4: Use the spam filter built into your phone
Fix 5: Block a number that keeps calling
Fix 6: Report scam attempts on Chakshu
Spam and DND: quick answers
Sources and further reading

Start here: match the problem to the fix

What keeps reaching you	What it is	What works
Sales calls from 140xx numbers, or SMS whose header ends in -P	Promotions from registered telemarketers	DND for all promotions or chosen categories; complain if they continue after you’ve blocked that category
Sales calls or SMS from an ordinary 10-digit mobile number	Unregistered telemarketing, which breaks TRAI’s rules	A complaint within 7 days (no DND needed), plus your phone’s spam filter
One number that won’t stop calling	A single persistent sender	Block it on your phone, and complain too
Fake KYC alerts, callers posing as police or CBI, job, loan or investment offers	Fraud attempts	A report on Chakshu
You’ve already lost money	Money lost to fraud	1930 or cybercrime.gov.in straight away, and a call to your bank
OTPs and other transactional SMS (-T), government messages (-G)	Transactional and government messages	Nothing to fix: DND doesn’t block these

Read the number or header before you answer

The number or header tells you two things: what kind of sender it is, and whether DND applies at all.

You see	Who’s behind it	Does DND stop it?
A call from 140xx	Promotional call from a registered sender	Yes, in the sectors you’ve blocked
A call from 1600xx	Service or transactional calls from banks and NBFCs, insurers, brokers, mutual funds, pension funds and government bodies	No
A call from 1601xx	Service or transactional calls from courier and logistics firms and from utilities (water, electricity, gas, LPG), on a series introduced in phases from August 2026	No
Header ending in -P	Promotional SMS	Yes
Header ending in -S	Service SMS	No. Only Fully Block, which TRAI is now scrapping, stops service messages sent on the basis of your consent
Header ending in -T	Transactional SMS, such as an OTP	No
Header ending in -G	Government message	No

Sources: TRAI’s regulations and press notes, checked on 10 October 2026.

Regulated finance firms had deadlines running from 1 January to 15 March 2026 to put their service and transactional calls on 1600 numbers. TRAI’s list covers banks, NBFCs, insurers, mutual funds, pension entities and qualified stockbrokers. With those dates gone, a caller on a plain 10-digit number claiming to represent your bank or insurer deserves extra suspicion. And never share an OTP over the phone.

COAI, the operators’ association, said in July 2025 that the -P, -S, -T and -G header suffixes were live on every network. Curious who is behind a particular header? TRAI’s lookup at smsheader.trai.gov.in will tell you.

Names on the incoming-call screen (CNAP)

CNAP (Calling Name Presentation) shows a caller’s name on screen, no app required. Under TRAI’s recommendation, that name comes from the caller’s SIM application form. TRAI recorded DoT’s view in October 2025: switch CNAP on for everyone by default, let customers ask their operator to disable it, and start with 4G and 5G subscribers.

Trade press reported operator pilots in November 2025, and operators have been turning CNAP on in stages since. Vi’s help page lists a VoLTE handset as a requirement and says that, for now, it shows names only when the call comes from another Vi number. We hadn’t seen any official statement by October 2026 that CNAP works on all networks or across operators. Treat the displayed name as a hint only: it tells you who the SIM is registered to, and nothing about whether the caller is safe.

Fix 1: Register on DND

Officially, TRAI calls DND “preference registration”. You’re telling your operator which commercial calls and texts you’d rather not get from registered senders (140-series numbers and -P SMS headers, for instance). Changing your mind later is fine; the setting can be edited any time.

Route	How to do it
Phone call	Dial 1909 from the number you’re registering and follow the voice menu.
TRAI DND app	Available for Android and iPhone. Confirm your number by OTP, then block everything promotional or pick categories.
Jio	In MyJio: Profile → Settings → Service settings → Do not Disturb.
Vi	myvi.in/dnd, or the Vi app.
Airtel	Its DND page at airtel.in (OTP needed).

Whichever route you use, keep the confirmation SMS: it has your reference number. Expect a short wait, too. Jio quotes up to 24 hours. Vi’s code of practice commits it to an acknowledgement within 15 minutes and implementation within 24 hours.

Note: You can text 1909 instead of calling. TRAI’s rules give the keywords: BLOCK PROMO (all promotions) and BLOCK 1 through BLOCK 8 (one category per number). Some operator pages haven’t caught up: Airtel’s blog and Jio’s help page mention START 0, and Vi’s FAQ says FULLY BLOCK. If you’re unsure, a call to 1909 avoids the guesswork.

Choosing a DND option

Option	What it blocks	What still gets through
Block Promo	Every promotional call and SMS, in all categories	Transactional, service and government messages
Category-wise (1 to 8)	Promotions in the categories you tick	Everything outside those categories
Fully Block (on its way out)	All promotions, plus consent-based service messages	OTPs and other transactional SMS, messages from the government, and service messages from businesses you have an existing relationship with

Verified on 10 October 2026 against two TRAI amendments to the TCCCPR (Second Amendment Regulations, 2025; Third Amendment Regulations, 2026).

Fully Block is going away. The Third Amendment to TRAI’s rules, notified on 18 September 2026, abolishes it. That takes effect once 30 days have passed since the amendment’s publication in the Official Gazette; operators then have 15 days to convert every Fully Block user to Block Promo. No action is needed from you, since Block Promo still shuts out promotions and lets service messages in.

Promotions fall into eight categories:

Banking, insurance, credit cards
Real estate
Education
Health
Consumer goods, automobiles
Communication, broadcasting, entertainment, IT
Tourism, leisure
Food, beverages

Beyond categories, you can restrict blocking by mode (calls, SMS or robocalls), by hours of the day and by days of the week.

Tip: If OTPs aren’t reaching you, DND can’t be the culprit, since none of its settings touch them. Our guide to missing OTP messages goes through what to check. Separately, every promotional SMS has to give you a way to opt out; once you do, that sender can’t seek your consent again for 90 days.

Fix 2: Complain about senders who break the rules

In February 2025 TRAI overhauled how spam complaints work, and these changes have all applied since mid-April 2025:

More time: you now have 7 days to complain after a call or SMS (the old limit was 3). File later and it’s treated as a report only.
Unregistered senders: telemarketing from regular 10-digit numbers isn’t allowed, so you can complain about such a sales call whether or not you’re on DND.
Registered senders: 140-number calls and -P SMS are permitted unless you’ve opted out of that category on DND, so get registered before complaining.
A valid complaint needs: the date, your number, the sender’s number or header, and a short description.

Choose a channel: your operator’s app or website, the TRAI DND app, or a call to 1909. Look for the UCC (spam) complaint option.
Select the offending call or SMS from your history, or attach a screenshot instead (operator apps must accept these). Check that the details are correct.
Submit it, and write down the complaint ID to follow up later.

What happens to the sender? Under the 2025 rules, complaints from 5 different people within 10 days trigger action against an unregistered sender, and the operator suspends its outgoing services during the investigation. If it is found at fault, it loses every outgoing service for 15 days on a first offence. A repeat offender is blacklisted, with all its connections disconnected for one year.

Two further changes arrive with the Third Amendment (notified 18 September 2026), though neither is live yet; both start 90 days from the amendment’s publication in the Official Gazette. First, the threshold drops: 3 complainants within 10 days will be enough to start action, on condition that the operator’s AI has flagged one or more of the sender’s numbers too. Second, you’ll get a right to appeal a complaint’s result through the same channels you complain on. The appeal window is 15 days after you learn the outcome or, if no outcome arrives within 15 days, the 15 days after that.

Fix 3: Use your operator’s spam warnings

According to TRAI (September 2026), every major operator now uses AI to detect suspected spam and alert its customers. Most of the time this means a warning label on the call; answering remains your decision.

Airtel: a “Suspected SPAM” label has appeared on likely spam calls and SMS since September 2024. Airtel describes it as free and automatically active for all customers (no app, no request), and says it flags harmful links inside SMS as well.
Vi: according to the Vi Protect page, the network labels likely spam on its own, free of charge: calls show “Suspected SPAM” and messages show “Vi Suspected SPAM”. The call labels require a VoLTE handset, but SMS labels work on any phone. You can also use the Vi app to report spam calls and block them.
Jio and BSNL: neither has an official page we could find explaining spam labels on calls. Jio, per news reports in October 2025, had started introducing spam warnings on incoming calls. BSNL announced in August 2025 that suspicious links in SMS were being blocked on its network, no setting required.

One limit applies to all of this: TRAI says calls from its official 140 and 1600 series must not be tagged as spam. Its September 2026 amendment goes further once it takes effect, stopping operator AI from flagging any 140xx, 1600xx or 1601xx number.

Fix 4: Use the spam filter built into your phone

Android phones running Phone by Google

Open the Phone app’s More options menu (three dots), then go to Settings → Caller ID and spam.
Leave See caller ID and spam on. It’s the default.
Enable Filter spam calls. Those calls won’t ring or show a missed-call alert, but they remain in your call history. Phones with automatic Call Screen keep this spam-blocking option inside Call Screen.

Spam texts are handled in Google Messages: tap your profile picture, then Messages settings → Protection and safety → Spam protection, and check that Enable spam protection is switched on. Google enables it automatically where the phone supports it.

Samsung phones

Open the Phone app, use its three-dot menu and choose Settings.
Turn on Caller ID and spam protection and accept with Agree.
Open Caller ID and spam protection again and enable Block spam and scam calls. Then pick between Block all spam and scam calls and Only block high-risk scam calls.

Smart Call on Samsung India’s site sends you to the same Caller ID and spam protection setting in call settings. The two option names are from Samsung’s Canadian support guide, so the wording may differ a little on your model or One UI version.

iPhone: calls and texts

Unknown numbers: Settings → Apps → Phone is the place. iOS 26 and later: set Screen Unknown Callers to Silence. iOS 18: turn on Silence Unknown Callers. Silenced calls land in voicemail and are still listed in Recents.
Spam calls: that same screen has a Spam filter to turn on (iOS 18 calls it Silence Junk Callers). It only works on calls your carrier labels as possible spam, and we couldn’t confirm that any Indian operator supplies such labels to iPhones, so don’t rely on it.
Texts: from iOS 26, open Messages, tap the filter button and go to Manage Filtering, where you turn on Screen Unknown Senders. Need OTP alerts to keep arriving? Tap Allow Notifications and enable the categories you want (choices differ by region). iOS 18 keeps this at Settings → Apps → Messages → Filter Unknown Senders. When Text Message Filter is on, unknown senders’ messages also get split into Transactions and Promotions.

Warning: Silencing strangers means some real callers get silenced too, such as a delivery agent or your clinic. Save the numbers of people you’re expecting calls from, and check the spam folder regularly.

At Mobivault, our experience is that older parents benefit most from silencing unknown callers. Customers who regularly get calls from new numbers, shopkeepers among them, have missed genuine calls with it on. Only switch it on if the calls that matter to you mostly come from saved contacts.

Should you install Truecaller or a similar app?

Caller ID apps of this type build their spam labels from user reports. Check what they ask permission for, contacts and call log included, and read the privacy policy before installing. TRAI’s rules stop such apps from tagging or blocking 140 and 1600 numbers; you yourself can still block whichever number you like.

Fix 5: Block a number that keeps calling

Phone by Google: find the call in your history, tap it and pick Block / report spam. Unblocking is under Settings → Blocked numbers, where the Unknown switch blocks private or hidden numbers only.
Samsung: in the Phone app, open the three-dot menu → Settings → Block numbers and add the number by typing it or picking from Recents or Contacts. There’s also a Block number button on the incoming-call screen.
iPhone: in Recents (Phone app), tap the info button next to the number and select Block Caller. Calls, messages and FaceTime from that number are all blocked. To unblock, open Blocked Contacts in Settings (its exact location varies with the iOS version).

Blocking stops one number only. Spammers simply switch to fresh ones, so file a complaint as well.

Fix 6: Report scam attempts on Chakshu

Chakshu is the Department of Telecommunications’ fraud-reporting service on Sanchar Saathi. Use it whenever a caller or message is out to defraud you. Common examples: investment scams, sextortion, job or loan offers, fake customer care, people claiming to be from the police, CBI, TRAI or DoT, and bogus KYC or bill-payment messages.

Open sancharsaathi.gov.in/sfc. In the Sanchar Saathi app, you can instead report directly from the call log or your SMS inbox.
Pick the medium (call, SMS or WhatsApp) and the type of fraud, and attach a screenshot.
Enter the sender’s number or SMS header, when it happened (the date and time must fall within the past 30 days), and a description that runs to 30 characters or more.
Next, enter the number that received it, confirm with an OTP, tick the declaration and send it.

Don’t expect a reply on your case: DoT says individual outcomes can’t be shared. If it came over WhatsApp, report the sender within WhatsApp as well. Sanchar Saathi also handles blocking a lost or stolen phone, should you ever need it.

Warning: Money already gone? Chakshu isn’t the place. Call 1930, the cyber crime helpline, or file at cybercrime.gov.in without waiting, and inform your bank.

From the Mobivault counter: Hardly anyone walks in just because of spam; it tends to come up while we’re configuring a customer’s new phone. Fed up with the calls? Bring the phone to us. We’ll do the DND registration together, by dialling 1909 or using the TRAI DND app, and we’ll have the spam filter running before you leave the shop.

Spam and DND: quick answers

Can DND block my OTPs or bank alerts?

No. Whatever DND setting you pick, transactional messages such as OTPs still get through.

I’m on DND. Why do sales calls still come?

DND has no say over unregistered senders. Sales calls from ordinary 10-digit numbers already break the rules, so complain within 7 days and switch the spam filter on. Remember that a fresh registration can need up to 24 hours to kick in, and businesses holding your digital consent can still send promotions.

How long do I have to complain?

You get 7 days from the call or SMS. Anything filed after that is treated as a report, not a complaint.

Must I be on DND to complain?

For promotions from registered senders, yes: block that category first. For unregistered senders, no.

Can government SMS be blocked?

No. Under TRAI’s rules, government messages (with -G headers) need no consent, and DND has no option to stop them.

A fraud call took my money. Do I report it on Chakshu?

No, Chakshu only takes attempted fraud. Report the loss at cybercrime.gov.in or on 1930 immediately, and phone your bank.

Spam Calls and Texts in India: Know the Sender, Then Pick the Fix

Start here: match the problem to the fix