With the rise in cyber threats and an increasing reliance on digital platforms, businesses must choose a suitable OTP delivery method to safeguard user accounts and transactions effectively. One-time passwords (OTPs) have become a cornerstone of secure authentication, offering businesses and users a reliable way to prevent unauthorized access.
These automatically generated, time-sensitive codes valid for 30 to 60 seconds protect against potential breaches by ensuring expired codes cannot be reused. SMS, USSD, and Voice SMS are the primary channels offering distinct advantages and challenges. This article compares SMS, USSD, and Voice SMS to help businesses make informed decisions and enhance their authentication processes.
A comparison of SMS, USSD, and Voice SMS for OTP Delivery
This comparison explores the strengths and weaknesses of SMS, USSD, and Voice SMS as methods for delivering one-time passwords (OTPs), helping businesses choose the most suitable option for secure authentication.
SMS( Short Message Service) for OTP delivery
Short message service (SMS) is a text-based service that delivers OTP directly to the user’s phone. It is a commonly used OTP delivery method because it is easy to use when users want to log in or sign in to their account on an application or website. It works by:
- The software will ask the user to generate an OTP code, which will be sent to their phone as an SMS.
- The user will get a six-digit OTP via SMS, usually valid for 1 to 2 minutes. The user must enter the code within this time, or it will expire. If it expires, they will need to request a new one.
- The user types in the OTP and securely enters the application or website. This additional security allows the software to protect itself from hacking and fraud.
Advantages of SMS for OTP delivery
These are some of the pros of using SMS OTP as your preferred delivery method:
- Accessible: SMS OTP is accessible on all mobile phones using the built-in messaging app. Users do not need to download any new apps; it works on smartphones and basic phones.
- Works offline: SMS OTP does not require an internet connection to work. You can quickly receive your OTP in areas with poor or no internet connection.
- Quick delivery: If you use SMS, you can receive your OTP in seconds. SMS OTPs are delivered in seconds, providing quick access to your accounts or transactions.
Limitations of SMS for OTP delivery
SMS OTP has several limitations, including:
- Network dependency: SMS OTP depends on the strength of the networks. If there are delays during network congestion, the user may not be able to get their OTP.
- Security vulnerabilities: SMS OTP is vulnerable to SIM swap fraud and interception. Attackers can exploit weaknesses in network providers to take control of a phone number and gain unauthorized access.
- Cost concerns: SMS OTP is generally more expensive than USSD. SMS charges for each message, regardless of whether the recipient receives it.
Best for
SMS OTP is best for areas with reliable mobile networks and general authentication.
USSD for OTP delivery
Unstructured Supplementary Service Data( USSD) is a feature that does not require a messaging app. USSD OTP is a temporary connection that delivers OTPs interactively without storing them on the user’s device. It does not save data on the phone. This is done by:
- The user initiates a USSD session by dialing the service’s specific code.
- The OTP is displayed directly on the phone screen during the session without being saved on the device.
Advantages of USSD for OTP delivery
The advantages of using USSD OTP are:
- No storage risk: OTPs are not stored on the phone, reducing the chances of phishing or hacking.
- Cost-effective: USSD is often cheaper for businesses than SMS or Voice OTPs.
- High security: The encrypted session ensures secure delivery of OTPs.
- Universal compatibility: USSD works on both basic and advanced mobile phones.
- Instant delivery: USSD OTP codes are quickly delivered, allowing users to access their accounts or transactions quickly.
Limitations of USSD for OTP delivery
The cons of using USSD OTP delivery include the following:
- Costly for users: While USSD OTP is cheap for businesses, some network operators charge users for USSD sessions. These charges may add up for frequent users.
- Session dependency: The user must complete the authentication within the session time frame. If the user is too slow, they must generate a new OTP.
- Network constraints: USSD requires active network connectivity and does not function in areas without USSD support. Poor network connections can result in failed sessions, which can be frustrating for users.
Best for
USSD is most effective for highly secure transactions in regions with users who rely on phones with basic features and instant delivery of OTP.
Voice SMS for OTP delivery
Voice SMS is a method of delivering OTPs through automated voice calls. Users receive a phone call containing an OTP, which they manually enter into the application or website.
- When a user initiates a login or transaction, the application requests an OTP.
- The user receives an automated voice call, which reads the OTP aloud.
- The user listens to the OTP, types it into the application or website, and gains access, completing the secure authentication process.
Advantages of Voice SMS for OTP delivery
Here are some of the benefits of using Voice SMS OTP as your preferred delivery method:
- Accessible to all literacy levels: Voice SMS is ideal for users who may not read or write. The spoken nature of the OTP ensures that users of all literacy levels can securely authenticate themselves.
- Bypass SMS issues: Voice SMS is beneficial in areas where network issues may delay delivery. The OTP is delivered without relying on text message systems as long as the call can connect.
- Personalized experience: Voice messages can be customized to support local languages and accents, enhancing user experience and accessibility, especially in regions with diverse linguistic backgrounds.
Limitations of Voice SMS for OTP delivery
While Voice SMS offers several benefits, it also has certain drawbacks:
- Privacy concerns: Users may feel uncomfortable receiving voice calls in public spaces. Listening to an OTP aloud could expose sensitive information to those nearby, raising privacy concerns.
- Missed calls: The OTP delivery is only successful if the user answers the phone or hears what the voice says. This can lead to delays or complications in time-sensitive transactions.
- Higher costs: Voice SMS is generally more expensive than SMS OTP due to the cost of voice calls, particularly when scaled to large numbers of users.
Best for
Voice SMS is best suited for users uncomfortable with written communication or in regions with low literacy levels. It is also an excellent choice for areas where SMS delivery might be more reliable and timely.
Choosing the best method for OTP delivery
When choosing the proper OTP delivery method for your business, it is essential to consider your target audience and specific needs. Here are some factors to help guide your decision:
Target audience:
If your users have basic phones or are located in rural areas with limited internet access, USSD or Voice SMS may be more appropriate. SMS is ideal for users with smartphones in regions with reliable mobile networks.
Security requirements:
If security is a primary concern, USSD offers encryption, making it an excellent choice for sensitive transactions. However, SMS may still be suitable for general authentication, and Voice SMS can provide an additional layer of security in diverse demographic regions.
Cost efficiency:
SMS may incur significant costs for businesses with a large user base, primarily if OTPs are frequently used. USSD offers a more cost-effective solution, while voice SMS, though reliable, comes at a higher price due to call charges.
Reliability and speed:
Consider the reliability of mobile networks in your target regions. If you live in an area with inconsistent SMS delivery, voice SMS or USSD may better ensure OTPs are delivered promptly.
Choose a reliable OTP service provider.
A good OTP service provider will offer you the best value for your money. A reliable OTP service provider should seamlessly integrate with existing systems, enable businesses to implement OTP solutions quickly, and enhance security. It should also provide detailed reporting and tracking of OTP requests. Arkesel is a reputable OTP service provider that provides these services and offers flexible pricing plans.
Bringing it all together: Choosing the best OTP solution.
Choosing the suitable OTP delivery method, SMS, USSD, or Voice SMS, depends on each situation’s unique needs. SMS stands out for its simplicity and accessibility but may encounter network delays and security vulnerabilities. USSD offers a secure, cost-effective option, though it demands active user involvement and consistent network access.
Voice SMS is great for people of all literacy levels but has higher costs and privacy issues. Businesses can improve security and user experience by allowing users to choose their preferred OTP delivery method. This approach makes the process more accessible, builds trust, and provides a smooth experience for users in different regions.
