WhatsApp vs SMS vs email for Indian businesses: cost, reach, rules and when to use each

Hemant Patil runs three two-wheeler workshops in Nashik with fourteen staff. He asked his nephew to find a “WhatsApp bulk SMS” service so he could tell 4,000 past customers about a monsoon service camp. The nephew came back with three quotes that had nothing in common. One was for SMS, one was for WhatsApp, and one promised both from an ordinary SIM.

The confusion is common, and it’s worth clearing up before any money moves. WhatsApp and SMS are different channels with different gatekeepers. Email is a third. Each has its own registration, its own consent rules and its own way of punishing a careless send.

The three channels side by side

	WhatsApp	SMS	Email
Who sets the rules	Meta	TRAI, enforced through telecom operators	Mailbox providers such as Gmail, plus general law
Before your first send	A number on the WhatsApp Business Platform and an approved template	DLT registration, a header and a registered content template	A sending domain with SPF or DKIM set up
Who you may message	People who opted in to messages from your business	Depends on category, consent and the customer’s registered preference	People who subscribed; marketing mail needs an unsubscribe link
Meta, operator or provider charge	Per delivered template, by category	Varies by provider and operator	Varies by provider
What the customer needs	WhatsApp and a data connection	Any mobile phone with signal	An email address they actually check
Can they reply to you	Yes, in the same chat	Usually not to a sender header	Yes

The rest of this article fills in each column.

WhatsApp: per-message prices set by Meta

To message customers first on WhatsApp, you need a number on the WhatsApp Business Platform and a template Meta has approved. Meta bills each delivered template by category. For Indian numbers, on the rate card effective 1 July 2026 and unchanged on 1 October 2026, before GST:

Message type	Per delivered message
Marketing template	₹0.8631
Utility template	₹0.115
Authentication template (OTP)	₹0.115
Free-form reply inside a 24-hour chat	First 1,000 per number each month at no charge, then ₹0.115

Hemant’s month might look like this: 2,600 “your vehicle is ready” utility messages at ₹0.115 is ₹299, and 1,500 service-camp offers at ₹0.8631 is ₹1,294.65. About ₹1,594 before GST, plus whatever his WhatsApp tool charges. The detail is in our WhatsApp pricing guide.

The rules that bite:

• Opt-in. The customer must have agreed to receive messages from your business, by name. A number on a job card isn’t that.
• Limits on new accounts. A new account can message 250 different people in a rolling 24 hours outside open chats, and 2,000 after verification. Hemant can’t send 4,000 on day one.
• A per-person cap. WhatsApp limits how many marketing messages each person gets from all businesses combined. Meta publishes no fixed number. A message held back by the cap fails with error 131049.

What WhatsApp does that the others don’t: the customer can answer. “Can I bring it Saturday instead?” comes back in the same thread, with a photo of the dented mudguard if needed.

SMS: TRAI’s DLT registration comes first

Commercial SMS in India is regulated by the Telecom Regulatory Authority of India under the Telecom Commercial Communications Customer Preference Regulations, 2018, usually shortened to TCCCPR. The regulations require operators to run a blockchain-based register, known as DLT, and a business can’t send a commercial SMS without being on it.

TRAI’s advice to senders lists the steps:

1. Register as a principal entity. That’s TRAI’s term for the business on whose behalf messages are sent. You do this on a telecom operator’s DLT portal.
2. Get a header: the alphanumeric sender name, up to 11 characters, that shows in place of a phone number.
3. Register each content template, with its fixed text and its variable parts marked.
4. If you send promotions that need consent, register a consent template and record customers’ consent through it.
5. Send through a registered telemarketer or provider, which passes your entity ID, header and template ID with every message.

Every message is checked against the registered template. If the text doesn’t match, the operator doesn’t deliver it. This is the usual reason a “bulk SMS” campaign shows as sent and nobody receives it.

The four SMS categories

TRAI amended the regulations on 12 February 2025. Among the changes, headers now carry a suffix that tells the customer what kind of message it is:

Suffix	Category	What it covers
-T	Transactional	A message in response to a transaction the customer started, sent within thirty minutes of it. OTPs are the standard example.
-S	Service	Information about a product or service the customer already has: delivery, warranty, a recall, a balance alert. Not promotional.
-P	Promotional	Anything containing promotional material or an advertisement. Must carry an opt-out in the same message.
-G	Government	Messages from government bodies.

The amended definition says that if promotional content is mixed into a transactional or service message, the whole message is treated as promotional. Promotional messages are delivered only to people who haven’t blocked that category in the preference register, or who have given consent. Customers set their preference through the short code 1909.

WhatsApp works the same way, as it happens. One discount line turns a utility template into marketing. Our piece on how Meta decides a message’s category covers that side.

What else the 2025 amendment changed

• Once a customer opts out, a sender may ask for their consent again only after 90 days. The customer can opt back in on their own at any time.
• Ordinary 10-digit mobile numbers may not be used for telemarketing. Commercial messages must come from registered headers.
• Operators act when a sender draws five complaints in ten days. Previously the trigger was ten complaints in seven days.
• For a first breach of that threshold, the sender’s outgoing services are barred for 15 days. For later ones, the sender’s telecom resources are disconnected across all operators for a year and the sender is blacklisted.
• Headers left unused for 90 days are deactivated until the sender asks for them back.
• Operators may ask senders for a security deposit that can be forfeited for violations.

TRAI put a further draft amendment out for consultation in 2026. Check the current text with your operator or provider before you plan a large send.

So the quote that offered bulk messages “from an ordinary SIM” was offering something TRAI’s rules prohibit, with a year-long blacklist as the downside.

What SMS costs

We won’t give a per-message figure, because there isn’t a single one. SMS pricing is set by your provider and the operators behind it, and it varies with category and volume. Operators’ DLT portals may also charge for registration. Ask for a written rate card that shows the price for each category you’ll use and any registration or header fees, and compare it on cost per delivered message.

Email: no regulator’s register, but mailbox providers have rules

There’s no DLT for email. Nobody approves your template. That freedom is why inboxes are full, and why Gmail and other mailbox providers now set conditions of their own.

Google’s sender guidelines, in effect since 1 February 2024, require every sender to Gmail accounts to authenticate their mail with SPF or DKIM. Anyone sending more than 5,000 messages a day to Gmail accounts must set up SPF, DKIM and DMARC, include one-click unsubscribe in marketing mail, and keep the spam rate that Google reports below 0.3%. Google’s own advice is to stay under 0.1%. Fall short and your mail goes to spam or is rejected, and you won’t get an error you can argue with.

Email prices vary by provider, and most charge by contacts stored or messages sent. Get a quote for your list size.

When India’s data-protection rules take full effect, consent duties will apply to every channel, email included. The dates are in our opt-in and DPDP guide.

”WhatsApp SMS blast”: why blasting fails on every channel

A blast means one message to everyone you have a number or address for. Each channel has a mechanism built to stop exactly that.

On SMS, promotional messages are filtered against preferences and consent, and five complaints in ten days is enough to start action. On WhatsApp, the per-person cap holds messages back, blocks and reports pull down template quality, and unofficial bulk tools get numbers banned; see bulk WhatsApp messages without a ban. On email, a high spam rate sends everything you write to the junk folder, including invoices.

The answer is the same each time: a smaller list of people who asked.

When each one wins

SMS wins when the message must reach any phone. An OTP has to arrive whether or not the customer has WhatsApp installed, data switched on or storage left. SMS is also the fallback for customers who never joined WhatsApp, which in Hemant’s case includes a fair number of older scooter owners. And it needs nothing from the customer: no app, no opt-in tap, no data pack.

Email wins for anything long or anything that needs filing. A tax invoice, an insurance renewal schedule, a fleet customer’s monthly statement: people expect these as attachments they can search for in a year. It’s the normal channel for business buyers, who read at a desk. There’s no 24-hour window and no template approval, so a newsletter can say what it likes at whatever length.

WhatsApp wins when you want the customer to answer, and when a picture helps. Pickup confirmations, “which slot suits you”, a photo of the worn brake pad with a price. We’d be wary of any vendor quoting an open-rate percentage, for any channel, without saying who measured it.

Where WhatsApp loses: it costs more per promotional message than its reputation suggests, new numbers start small, and an offer sent to someone who didn’t ask can get you blocked in one tap.

Using them together

For Hemant, a sensible split looks like this:

• Vehicle ready, pickup reminder, payment received: WhatsApp utility templates to customers who opted in, with SMS for those who didn’t or who aren’t on WhatsApp.
• OTP for the customer login on his booking page: SMS, or a WhatsApp authentication template with SMS as the fallback.
• The monsoon service camp: WhatsApp marketing to customers who opted in to offers. Not SMS to all 4,000.
• Invoices and fleet statements: email.

Don’t send the same message on all three at once. A customer who gets the camp offer by WhatsApp, SMS and email in the same hour will complain on whichever is easiest.

Keep one record of consent per customer, per channel. Agreeing to WhatsApp updates isn’t agreeing to promotional SMS, and an opt-out on one should make you think hard before using another.

If terms such as template, utility or customer service window are new, the WhatsApp Business glossary defines them, and the WhatsApp marketing guide goes deeper on campaigns.

Before paying anyone, Hemant should ask each vendor one question: which channel is this, and whose rules does it run under? If the answer isn’t Meta, a DLT-registered header or an authenticated domain, the quote is for something that will stop working, probably mid-campaign.