Voice OTP vs SMS OTP in India (2026): Cost, DLT and Reach

Voice OTP and SMS OTP solve the same problem in different ways. SMS OTP is billed per message and, in India, needs a DLT-registered sender ID and template before it is delivered. Voice OTP is a phone call that reads the code aloud, billed per answered minute, with no SMS DLT template, and it reaches landlines and feature phones. Most teams use SMS first and voice as the fallback.

Add voice OTP to your login: Open the Voice OTP portal and send your first code through the API.

Side by side

	SMS OTP	Voice OTP (Edesy)
How the user gets the code	Text message on the phone	A call that speaks the code, usually twice
How it is billed	Per message (per SMS segment), at your SMS provider's rate	Rs 1.50 per answered minute, 1-minute minimum, plus 18% GST
Unanswered or undelivered	Depends on your SMS provider's terms	Unanswered calls are not charged
DLT registration in India	Entity, sender ID (header) and content template must be registered	No SMS DLT template needed
Phones it reaches	Phones that can receive SMS	Any phone that can answer a call, including feature phones and landlines
Works for users who can't read the screen easily	Not well	Yes, the code is spoken
Monthly fee	Depends on provider	None
Delivery proof	Delivery report (if your provider returns one)	Call log with timeline, DTMF response and hangup cause; callback with status

We have not put SMS prices in this table on purpose. SMS rates vary by provider, volume and route, and you already know yours. The useful comparison is your own SMS rate against Rs 1.50 for a voice OTP, but only on the OTPs that SMS failed to deliver.

How the cost structures differ

SMS OTP is a per-message cost. If a message has to be split into several segments (for example a long template or a non-English script), each segment can be billed. Resends cost again. Some providers also have setup, sender ID or monthly charges.

Voice OTP on Edesy is a per-minute cost:

Rs 1.50 per answered minute, billed in 1-minute steps with a 1-minute minimum.
A short template ("Your code is 4 8 2 9 1 3. I repeat, 4 8 2 9 1 3.") finishes inside a minute, so it costs Rs 1.50 plus GST.
Unanswered, busy and failed calls are not charged.
No monthly fee, paid from a prepaid INR wallet topped up with Razorpay, with GST invoices.

So voice is not trying to be cheaper than SMS per message. It is a way to reach the users SMS did not reach, at a known price per successful call. See Voice OTP pricing for the full details.

DLT: what SMS needs and voice doesn't

Under TRAI's commercial communication rules, business SMS in India goes through DLT (Distributed Ledger Technology) platforms run by the telecom operators. Before an OTP SMS is delivered you generally need:

A registered business entity on a DLT platform.
A registered sender ID (header).
An approved content template, with the variable part (the code) marked.
Messages that match the template; mismatches can be blocked.

If you change the wording of your OTP SMS, the template usually has to be approved again. Rules and operator processes change, so check the current requirements with your SMS provider.

Voice OTP does not use an SMS template, so there is nothing to register on the SMS side. You set the spoken text yourself with a {{otp}} placeholder and can change it at any time. Voice calls have their own telecom rules, so keep OTP calls purely transactional: no offers, no marketing lines. Our post on TRAI rules for AI calling covers the wider picture.

Who SMS misses and voice reaches

SMS OTP fails quietly for some users:

Landline users. Business users often sign up with an office landline that can't receive SMS.
Feature phones and older handsets. SMS may arrive, but small screens and full inboxes make it easy to miss.
Users who struggle to read the screen. Elderly users, users with low vision and users with limited literacy can listen more easily than read.
Delayed or filtered messages. When an SMS is delayed, the code can expire before it lands.

Voice OTP works on any phone that can answer a call, and the code is spoken in the user's language (en-IN, en-US, Hindi and others). You can also turn on press-1 confirmation so the user confirms they heard the code.

When to use which

Situation	Recommended
Normal app or web login on smartphones	SMS first, voice as fallback
User entered a landline number	Voice only
User tapped "Didn't get the code?"	Offer "Call me with the code"
Older or low-literacy user base	Voice first, or offer both up front
High-value action (payout, change of bank details)	Either, plus press-1 confirmation on voice

The fallback pattern is covered step by step, with an API example, in how to add voice OTP fallback to your login. If you're new to how the call itself works, start with how voice OTP works.

How to switch on voice OTP

Sign up on the Voice OTP portal and top up the wallet.
Create an API key (keys look like sk_...).
Set defaults once: language, message template with {{otp}}, press-1 confirmation, retries on no-answer and a callback URL.
Call the API POST https://voice-api.edesy.in/v1/voice-otp/send with the phone number. Send your own code or let Edesy generate one.
Read the result from the callback or the call log, and verify the code in your app as you do for SMS.

The full request and response format is in the Voice OTP docs.

Things to watch

Rate limits. Voice OTP has a per-number, per-hour limit so a bot can't make your app call one number again and again. Keep it on.
Code expiry. A call takes longer than an SMS to arrive and be heard. Give voice codes the same or a slightly longer validity window.
Script length. Every extra sentence adds seconds. Read the code twice and stop.
Same code, two channels. If you send voice after SMS, decide whether to reuse the SMS code or issue a new one, and invalidate the old one if you issue a new code.

Bottom line

SMS OTP stays the default for most smartphone logins because it's familiar. Voice OTP fills the gaps: landlines, feature phones, users who can't read the screen easily and messages that never arrive. Run both, compare on your own numbers, and use the Voice OTP product page to see what's included.

Start on the Voice OTP portal, or book a demo if you want to talk through volumes first.

Frequently asked questions

Is voice OTP cheaper than SMS OTP in India?

Usually not per message. SMS is billed per message (per segment), while voice OTP is billed per answered call-minute. On Edesy a voice OTP costs Rs 1.50 per answered minute with a 1-minute minimum, plus 18% GST, and unanswered calls are not charged. Compare it against your own SMS rate, and count only the OTPs that SMS failed to deliver.

Do I need DLT registration to send voice OTP?

Voice OTP does not need an SMS DLT template. SMS OTP in India needs a registered entity, a sender ID (header) and an approved content template on a DLT platform before messages are delivered. Voice calls follow their own telecom rules, so keep OTP calls strictly transactional.

Does voice OTP work on landlines and feature phones?

Yes. A voice OTP is an ordinary phone call that reads the code aloud, so it reaches any phone that can answer a call, including feature phones and landlines. SMS needs a phone that can receive and display text messages.

Should voice OTP replace SMS OTP?

For most apps, no. The common pattern is SMS first and voice as a fallback when the SMS has not arrived after a short wait, or voice first for users on landlines, feature phones or with low literacy.

How long does a voice OTP call last?

A short template that reads the code twice usually finishes well inside a minute, so it is billed as one minute on Edesy. Longer messages or a press-1 confirmation step add seconds, so keep the script short.

Can I see whether a voice OTP was delivered?

Yes. Each Edesy voice OTP call has a log with a timeline, the DTMF key pressed (if confirmation is on) and the hangup cause, and the result is posted to your callback URL as delivered, no-answer, busy or failed.