Authenticate and verify your users using SMS OTP and Voice OTP services

What is OTP service?

OTP service is the easiest way of verifying user information and authenticating online transactions. Used by businesses to boost data security and prevent phishing attacks, an OTP service provider ensures timely delivery of OTPs to the right customers via SMSes and voice calls.

How OTP service works

Verification request

Customer clicks on the ‘Verify’ button on your app or website and a unique OTP is generated in your backend system

Exotel verification

Exotel fetches the generated OTP and sends it to your customer’s registered mobile number (This can be done either through SMSes or voice calls)

Number is verified

Your customer enters the unique OTP sent by Exotel on your app or website and gets verified instantly

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Types of OTP services

SMS OTP Service

Send OTPs to your customers using SMSes. Exotel provides reliable OTP SMS services with high deliverability and low latency.

Voice OTP Service

Verify your customers using voice OTP service. Make automated voice calls and play a sequence of digits to verify the registered mobile numbers.

How can businesses use OTP service

Two-factor authentication (2FA)

Implement an extra layer of security in your systems, without adding complexity to your customers.

Spam prevention

Effectively control spam registrations, and avoid fake signups. Optimize and secure your backend systems against spam.

Password Resets

Instead of sending codes or links via email, use the OTP service to verify users before password resets.

Passwordless logins

Do away with passwords as your customers can be verified using an OTP every time they log in to your system.

Account Reactivations

Reactivate a user account with a confirmed acceptance from them. Use OTP verification as a means of verifying identity.

Transaction Authentication

Keep all transactions safe and sound. Add an additional layer of security with OTP verification to ensure safe transactions.

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How enterprises benefit from Exotel’s OTP solutions

A glimpse at how Go-Jek used Exotel’s OTP verification solution to push their delivery rates to 92%

Advantages of Using OTP Services


Exotel is an OTP service provider that grows with you. Pay as you scale and never overspend on your resources.

No Delay

Don’t keep a customer waiting for any more than 8 seconds. Our OTP service ensures timely delivery of the OTP messages.

Operational Efficiency

Send thousands of OTP verification messages without having to run multiple numbers. Our OTP service can handle them all!

Crafting Connected Customer Conversations for Enterprises Globally

Customer Experiences That Speak Volumes

The Exotel Advantage

Superior Quality

Best success rates, voice quality and reduced latency

Scale at Ease

Grow at will, expand without worrying about infrastructure

Superior Reliability

Best in class uptimes of 99.94% including operator uptimes

Best Support

24×7 customer support via phone, email and Twitter

Simple to implement

Sign up and get started in less than 30 minutes, integrate easily using our REST APIs

Extensive Reporting

Easy to understand, detailed reports sent every day


‘OTP’ stands for ‘One-Time Password’, and as the name implies, OTPs are used to authenticate and verify users whenever they initiate a transaction or a session on your app/website. However, to send OTPs to your customers’ mobile numbers you will need an OTP service provider like Exotel. Exotel provides OTP services like SMS OTP Service, Voice OTP Service, and missed call verification services. To know how to use our OTP solutions for your business, schedule a callback from our experts.

To put it in simple terms, this is how it works:
1. Your customer clicks on the ‘Verify’ button on your app or website.
2. A unique OTP is generated in your backend system.
3. Exotel sends the same generated OTP to the customer’s registered mobile number (This can be done through SMS or voice call).
4. Your customer enters the unique OTP sent by Exotel on your app or website.
5. If the entered OTP matches with the generated OTP, the customer is marked as verified. Get our free ebook - ‘Exhaustive guide on 2-factor authentication’.

Passwords have been the primary form of customer authentication since the beginning of the internet. However, having a password-only authentication system will put businesses at an increased risk of data breaches, phishing attacks, and security threats. Therefore, most businesses use OTP services to implement two-factor authentication (2FA) into their login systems or transaction portals. With two-factor authentication enabled, your customers will need a one-time password or OTP (in addition to their registered password) to complete the transaction. To know more about 2FA, download our free ebook - ‘Exhaustive guide on 2-factor authentication’.

Any business that deals with sensitive customer information can make use of our OTP services. Some examples of the sectors that use OTP services are banking, healthcare, e-commerce, insurance, transport, etc. You can schedule a callback from our experts to understand how to implement an OTP-based authentication system for your business. 

It’s fairly simple. All you need to do is sign-up on our website and a dedicated account manager will get in touch with you to help you set-up the OTP authentication system for your business. You will also get a 15-day free trial to test our OTP services before making your buying decision. Start your 15-day free trial

The cost of our OTP services is based on your estimated monthly usage. To get effective prices and volume-based discounts, contact our sales team. 

Choosing a reliable OTP service provider in India is the key to implement a robust authentication system. Below are some of the important factors to consider:
1. Delivery and Latency Rates: Always choose a provider that can assure you of better OTP delivery rates and lower latency rates.
2. Flexible APIs: If you are implementing an OTP authentication system using APIs, then make sure that your OTP service provider’s APIs are flexible and easy to implement in your backend systems.
3. Data Security: Your customers’ data should be your number one priority. Always choose a provider that is ISO certified and exercises enterprise-grade security practices.
4. Scalability: Always choose a provider that can quickly scale up or down according to your business needs.
5. Customer Service: Choose an OTP service provider that values your time and truly cares about your success. Always ask if you are getting timely support in case you run into problems.

Exotel follows industry-leading security best practices. We power SMS communication for various banks & healthcare providers and our security practices meet all of their regulatory requirements. In fact, this is what Zivame has to say about the security of the Exotel platform: “We’ve been using Exotel for 4+ years now and haven’t experienced any security incidents/data breaches. Exotel’s platform is quite secure.” 

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