How to Send OTP to Nepal: SMS APIs, Sender IDs, and Costs

If your application needs to send OTPs to users in Nepal, delivery issues can prevent customers from completing sign-ups, logging in, or confirming payments.

These issues can arise when your messaging provider has unreliable delivery routes to Nepal Telecom or Ncell, your sender ID isn’t properly configured, or your application rejects valid Nepali mobile numbers.

Repeated verification requests, delayed messages, and failed delivery attempts can also increase costs, especially for businesses serving users across multiple countries.

In this guide, we’ll explain how to send and verify OTPs to Nepali phone numbers, the requirements you need to consider, and how to improve delivery reliability while keeping verification costs under control.

How to Send OTP to Nepal Using an API

To send OTPs to Nepali phone numbers, you’ll need a messaging provider that supports delivery to Nepal, a properly configured sender ID, and an application that generates and verifies one-time passwords.

The process typically involves sending a verification code when the user requests it, delivering it through a mobile network, and verifying the user’s input before allowing them to complete an action.

Here’s how to set it up.

1. Choose an OTP Provider That Supports Nepal Telecom and Ncell

Nepal has two major mobile network operators, Nepal Telecom (NTC) and Ncell. Your messaging provider should support reliable OTP delivery to users on both networks.

For businesses operating primarily in Nepal, Sparrow SMS provides a local SMS gateway API that businesses can integrate into their applications to send OTPs, transactional notifications, and other automated messages.

If your application also serves users in multiple countries, you may want a provider that manages OTP generation, verification, and delivery across different messaging channels.

For example, SecondFactor offers an OTP verification API that supports SMS, WhatsApp, Viber, and RCS. Its routing engine automatically selects the lowest-cost eligible channel for each request and attempts another available channel when delivery isn’t confirmed.

This allows applications to send and verify OTPs through one integration instead of building separate channel-selection and fallback workflows for every market.

When evaluating an OTP provider, consider the following:

• Delivery reliability: Confirm that the provider supports Nepal Telecom and Ncell and provides reliable routes for reaching users on both networks.
• Sender ID support: Check whether you can register a sender ID and what documents the provider requires.
• Verification management: Determine whether the provider handles OTP generation, expiration, and verification or whether your application must manage these functions.
• Alternative delivery channels: Check whether you can use WhatsApp, Viber, or other channels if SMS delivery fails.
• Pricing: Compare message costs, verification fees, and additional charges for repeated attempts.
• Delivery reporting: Look for delivery receipts, error information, and verification logs that help you identify failed messages.

You should also confirm that your provider uses authorized delivery routes.

In July 2025, the Nepal Telecommunications Authority (NTA) warned against unauthorized termination of international A2P SMS, citing Nepal’s telecommunications licensing requirements.

For applications sending verification messages into Nepal from overseas, ask your provider how it delivers messages to local operators and whether its routes comply with the applicable requirements.

2. Format Nepali Phone Numbers Correctly

Nepali mobile numbers contain 10 digits and generally begin with 97 or 98.

For international messaging, phone numbers use the E.164 format, which combines the country code with the subscriber number.

The format accepted by your SMS provider may differ.

For example, Sparrow SMS’s domestic SMS API accepts 10-digit local mobile numbers, while international verification APIs generally expect numbers in E.164 format.

Your application should normalize numbers into the format required by the API you’re using.

Avoid restricting validation to a fixed list of mobile prefixes because Nepal’s operators can introduce new number ranges.

For example, Ncell started issuing mobile numbers beginning with 971 in December 2025. It also asked banks, applications, and other service providers to update their systems to accommodate the new range.

If your application only accepts older Ncell prefixes such as 980, 981, 982, and 970, users with newer 971 numbers may be unable to request an OTP.

Use an up-to-date phone number validation library or numbering data source rather than maintaining a restrictive list of prefixes.

3. Set Up Your SMS Sender ID

A sender ID identifies the business or application sending an SMS. Instead of displaying an unfamiliar number or generic sender name, an alphanumeric sender ID can display your business name.

For example, a verification message from an application called MyApp could appear under the sender name MYAPP.

Depending on your messaging provider, you may have the option to use a shared sender ID or register a dedicated sender ID for your business.

Sparrow SMS supports both options, with dedicated sender IDs available under its business messaging packages.

A dedicated sender ID helps users recognize verification messages from your application, although it may involve additional registration requirements and costs.

Before registering, check with your provider about the required business documents, sender name restrictions, and approval process for Nepal Telecom and Ncell.

If you’re sending OTPs through multiple channels, you may also need separate sender registration or business account approvals for WhatsApp, Viber, or RCS.

Complete these requirements before launching your verification system to avoid unnecessary delays.

4. Generate, Send, and Verify the OTP

Once your messaging provider and sender ID are configured, you can connect OTP delivery to your application’s sign-up, login, password reset, or transaction verification process.

A typical OTP verification flow works as follows:

1. The user enters their phone number and requests a verification code.
2. Your backend validates the number and generates a one-time password or requests one from your verification provider.
3. The messaging provider delivers the code to the user’s phone.
4. The user enters the received code into your application.
5. Your backend or verification provider checks the code and confirms whether it is valid.

For most applications, a six-digit numeric code with a short expiration period, such as five minutes, provides a familiar verification experience.

You should also make each code single-use, limit the number of incorrect attempts, and prevent users from repeatedly requesting new codes within a short period.

If you’re using a basic SMS API, your application will generally need to manage OTP generation, secure storage, expiration, and verification.

For example, the Sparrow SMS API uses a /sms/ endpoint with parameters for the API token, sender ID, recipient number, and message content. You can follow its SMS API integration guide to connect SMS delivery to your application.

If you’re using a managed OTP verification API, the provider can handle code generation and validation, reducing the verification logic your development team needs to maintain.

Your SMS should clearly identify the application and provide the code without unnecessary information.

For example:

Your MyApp verification code is 123456. It expires in 5 minutes. Do not share this code.

Keep your API credentials on the server rather than exposing them in client-side applications. You should also avoid logging raw verification codes or returning them in API responses.

5. Set Up Retries and Alternative Delivery Channels

Even with a reliable SMS provider, some messages may arrive late or fail to reach the recipient.

Temporary network issues, carrier congestion, and unavailable mobile coverage can all affect OTP delivery.

Your application should allow users to request another code after a reasonable interval. A resend delay of 30 to 60 seconds gives the original message time to arrive while preventing unnecessary requests.

You can also offer alternative delivery channels for users who cannot receive SMS.

For example, WhatsApp and Viber can deliver verification codes over an internet connection, making them useful options when traditional SMS delivery is unavailable.

However, you must complete the relevant business account setup, sender approvals, and authentication templates before using these channels.

Some OTP verification platforms can automatically select eligible channels based on destination pricing and delivery availability, then attempt a fallback when the initial message isn’t delivered.

If you’re implementing retries yourself, make sure your application doesn’t generate conflicting active codes or trigger several overlapping delivery attempts.

Your fallback process should also account for users who don’t have WhatsApp, Viber, or another supported messaging application installed.

6. Test OTP Delivery on Both Nepali Mobile Networks

Before launching your verification flow, test it using actual Nepal Telecom and Ncell mobile numbers.

An API response indicating that a message was accepted doesn’t necessarily mean the recipient received it.

Check whether the message arrives promptly, displays the expected sender name, and contains the correct verification code.

You should also test:

• Valid mobile numbers on both Nepal Telecom and Ncell, including newer prefixes such as 971.
• Incorrectly formatted and invalid mobile numbers.
• OTP expiration, repeated requests, and incorrect verification attempts.
• Delivery when your primary messaging channel fails or becomes unavailable.
• Successful verification after the user receives the message.

Once your application goes live, monitor both message delivery rates and completed verification rates.

A high delivery rate doesn’t automatically mean users are successfully verifying their accounts. Delayed codes, expired sessions, and confusing verification screens can still prevent users from completing the process.

How Much Does It Cost to Send OTPs to Nepal?

The cost of sending OTPs to Nepal depends on your messaging provider, monthly verification volume, delivery channel, and whether you need a dedicated sender ID.

For local SMS delivery, Sparrow SMS offers volume-based pricing, with lower per-message rates available for businesses that purchase larger quantities of SMS credits.

Its packages include Starter, Growth, Business, and Enterprise options, with API integration and delivery to both Nepal Telecom and Ncell.

Sparrow SMS doesn’t publish one fixed per-message price for all recurring API traffic because the rate depends on volume and service requirements.

According to its pricing information and FAQs, the company generally charges NPR 2.50 plus VAT per SMS for its one-time sending service. This is a separate service for short-term or single-use messaging requirements, not the standard quoted rate for ongoing OTP API traffic.

For regular OTP delivery, businesses can request a customized quote based on their expected message volume and sender ID requirements.

When estimating verification costs, account for more than the first message.

If users request several codes before completing verification, your application may incur multiple message charges. Failed attempts and fraudulent verification traffic can increase your bill further.

The length and encoding of your SMS messages can also affect pricing.

A standard GSM-7 SMS supports up to 160 characters in a single segment, while messages containing Nepali script or other Unicode characters generally use UCS-2 encoding, which supports up to 70 characters in a single segment.

Longer messages may be divided into multiple billable segments, so keep your OTP templates concise while using language your users can understand.

For businesses processing large verification volumes, the most useful metric is the cost per completed verification rather than the price of an individual SMS.

This accounts for unsuccessful attempts, additional messages, and the number of users who actually finish verification.

You can reduce unnecessary OTP expenses by limiting repeated requests, blocking suspicious traffic, keeping messages short, and choosing cost-effective delivery channels when they are available to the recipient.

Why OTPs Sometimes Fail to Reach Nepali Phone Numbers

If users report that they aren’t receiving verification codes, start by checking the provider’s delivery status and the mobile network associated with the affected number.

Common problems include:

If problems affect only one operator, compare delivery results by network before making changes to the entire verification system.

If messages appear to reach users but few complete verification, review the verification screen, code expiration period, and resend process.

You should also protect your application against SMS pumping, where automated requests generate large volumes of unnecessary OTP messages.

Rate limits based on phone number, IP address, and device can help reduce this traffic. For sensitive actions such as financial transactions, consider additional authentication controls rather than relying exclusively on SMS OTPs.

Conclusion

Reliable OTP delivery in Nepal depends on choosing a provider that supports both Nepal Telecom and Ncell, configuring your sender ID correctly, and building a verification process that handles failed deliveries without creating unnecessary costs.

Your application should also accept valid Nepali phone numbers, including newer prefixes, and give users a way to request another code when the first attempt fails.

For businesses primarily serving Nepali users, a local SMS provider such as Sparrow SMS can provide the API connectivity and support needed to deliver verification messages.

If your application serves users across multiple markets, consider how your provider handles verification, channel selection, and fallback so you can manage delivery reliability and costs without maintaining separate workflows for every destination.

Before launching, test your OTP verification flow on both mobile networks and continue monitoring delivery and verification performance as your traffic grows.