Every serious business in Zambia today is up against the same challenge. The question of how to securely authenticate users and minimize costs. Banks, fintech apps, eCommerce stores, and even government services need to determine identity before granting access. The most widely used mechanisms are one-time passwords (OTPs) sent via SMS or voice call.
Both methods achieve the same goal but work in different ways. SMS OTP is cheap and familiar. Voice OTP is more reliable when networks fail. The choice isn’t always obvious. This article compares SMS and Voice OTP in Zambia, weighing their pros, cons, costs, and security. It also shows how a hybrid model can help businesses achieve both efficiency and trust.
How OTP Works in Zambia
An OTP is a unique code sent to a user’s phone for login, payment approval, or registration.
- SMS OTP delivers the code by text message.
- Voice OTP delivers it through an automated voice call that reads the digits aloud.
Users then enter the code on a website, app, or USSD prompt. In both cases, the OTP expires quickly, usually within two to five minutes. OTP is now standard in Zambia for everything from banking transactions to online shopping, making delivery reliability a business-critical issue.
SMS OTP: Strengths and Weaknesses
Strengths
- Affordable at scale: Sending an SMS is cheap. Bulk pricing in Zambia makes SMS cost-effective for thousands of messages.
- User familiarity: Almost every mobile user knows how to read and enter a code from a text.
- Fast delivery: In ideal conditions, SMS reaches the phone in seconds.
- Works on feature phones: No internet or advanced device needed.
Weaknesses
- Delivery delays: Network congestion or international routing can delay SMS by minutes. For OTP, that delay kills the process.
- SIM swap fraud: Criminals can hijack a user’s number and intercept SMS OTPs.
- Spam filtering: Some SMS routes face filtering issues, especially with promotional content.
- Poor reliability in rural zones: Network issues in rural Zambia sometimes block delivery.
Voice OTP: Strengths and Weaknesses
Strengths
- Higher reliability: Voice calls often succeed where SMS fails, especially on weak networks.
- Security edge: Harder to intercept than SMS, reducing fraud risk.
- Accessibility: Users with basic literacy or vision problems can still hear the code.
- Trust factor: A phone call feels more personal and urgent than a text.
Weaknesses
- Higher cost: A voice call costs more than a text. Businesses pay extra for reliability.
- Missed calls: If the user doesn’t answer, the OTP is lost.
- Language barriers: If the call isn’t localized, users may struggle to understand.
- Scalability challenges: Handling thousands of calls at once needs stronger infrastructure.
Cost Comparison in Zambia
Costs matter. A single SMS in Zambia can cost a fraction of a cent with bulk discounts. Africala lists rates that make SMS feasible even for startups.
Voice OTP, on the other hand, involves call charges. Even with optimized routing, one voice call can equal several SMS messages in price.
The trade-off: SMS OTP is cheaper but less reliable. Voice OTP is pricier but ensures delivery in critical transactions. When businesses weigh user experience against budget, many find that the extra cost of voice calls is justified in situations where failed verification could mean losing a customer.
Security and Compliance
- SMS OTP risks: Vulnerable to SIM swap, number recycling, and message interception.
- Voice OTP risks: Missed calls or noisy environments reduce effectiveness, but interception is less likely.
- Regulation in Zambia: Telecom authorities require user consent and respect for privacy. Both SMS and Voice OTP must comply.
A hybrid approach often helps meet compliance while adding a security layer. For example: send an SMS first, then switch to Voice if undelivered. This dual system shows regulators that a business takes security seriously while still respecting user convenience.
When to Choose SMS, Voice, or Hybrid
- Choose SMS OTP when you need low-cost, mass-scale verification for non-critical actions. Example: signing up for a free service.
- Choose Voice OTP when you must guarantee delivery, such as for bank transfers, insurance claims, or high-value eCommerce purchases.
- Choose Hybrid when your business can’t afford failure. SMS goes out first. If not delivered within a set time, Voice OTP triggers automatically.
Hybrid Strategy: The Future of OTP in Zambia
Forward-thinking businesses in Zambia already use hybrid strategies. They start with SMS to save costs. If delivery fails, a voice call ensures no user is left behind. This balances affordability, reliability, and security.
Africala’s platform supports both SMS and Voice OTP, making it easier to integrate a layered system. By combining the two, you reduce fraud, increase user trust, and avoid costly failed verifications. As digital services in Zambia expand, a hybrid OTP strategy will likely become the new standard.
FAQs
How reliable is SMS delivery in Zambia?
SMS delivery rates in Zambia are generally high, but they can drop during network congestion or outages. Some messages may also be delayed if users are in remote areas or using smaller carriers.
Does Voice OTP work on feature phones and landlines?
Yes. Voice OTP works on any device that can receive calls, including feature phones and landlines. This makes it useful in rural areas where smartphones are less common.
Can Voice OTP be automated for large-scale verifications?
Absolutely. With the right provider, Voice OTP can be fully automated to verify thousands of users simultaneously without manual intervention.
Are there compliance requirements for using OTP services in Zambia?
Yes. Businesses collecting or verifying user data must comply with Zambia’s ICT and data protection regulations. Using secure OTP delivery methods like Voice can help meet those requirements.
How do businesses integrate Voice OTP into existing systems?
Most providers offer APIs that connect directly with your app, website, or CRM. The integration process usually takes a few hours to a couple of days, depending on complexity.
Conclusion
There is no single winner in the SMS vs Voice OTP debate. It will depend on what is a priority to you. SMS is cost-effective, easy to use, and fast, but it has a tendency not work as well on a poor network. Voice OTP relies on the customer having a good network connection and usually costs more and takes longer to deliver the OTP to the end-user than SMS OTPs.
For businesses in Zambia, the best path forward is a hybrid model that uses both methods smartly. Africala enables this balance with scalable OTP services designed for the Zambian market. Choosing the right mix today means fewer failed verifications, happier customers, and stronger long-term growth.