SMS OTP API for Africa — The Complete Guide

Why OTP delivery is different in Africa

Africa is the largest mobile-first market in the world. Most users interact with your product exclusively through a phone, and SMS is the only universally available channel for verification — smartphone penetration for push-based authenticators is still low in many regions. But delivering an OTP reliably in Africa is not the same problem as delivering one in London or San Francisco.

The Nigerian DND registry

Nigeria operates a Do Not Disturb (DND) registry managed by the NCC. Subscribers can opt out of promotional messages, and many have — either intentionally or by default. The catch: poorly classified OTP traffic can be filtered as promotional and silently dropped. A provider with direct transactional routes and proper sender ID classification is the difference between a delivered OTP and a silent drop.

A fragmented carrier landscape

Each country has its own set of carriers, sender ID rules, and interconnect agreements. There is no single "African SMS" route. The table below shows the major carriers per market and a delivery nuance for each.

Why international providers struggle

Global providers like Twilio and Vonage route African SMS as international traffic through aggregator chains. This means higher latency, per-message costs of $0.31–$0.39 in Nigeria, and no direct relationship with the local carrier that actually delivers the message. They also cannot reliably bypass the DND registry and often lack alphanumeric sender IDs in markets that require pre-registration. We do not publish a delivery percentage for Robase or for aggregators; the practical difference is local transactional routes and a fallback provider when the primary fails.

The case for multi-provider failover

No single carrier in Africa is reliable 100% of the time. MTN Nigeria can have a two-hour window where OTP traffic stalls; Safaricom Kenya occasionally throttles aggregator traffic during peak billing cycles. A provider that routes through multiple carriers per country and fails over automatically — without you writing retry logic — keeps OTPs moving when one upstream fails. Credits are refunded when every configured provider fails. This is the single most important feature to look for.

How SMS OTP works

The flow is two calls: send a code to a phone number, then verify the code the user types back. Robase exposes a simple REST API with Bearer token auth. Below are examples in curl, Node.js, PHP, and Go.

# Send a 6-digit code valid for 10 minutes
curl -X POST https://api.robase.dev/v1/otp/send \
  -H "Authorization: Bearer robe_your_api_key" \
  -H "Content-Type: application/json" \
  -d {"phone_number":"+2348012345678","code_length":6,"ttl_seconds":600}

# Response
{"otp_id":"01HXY...","status":"sent"}

curl -X POST https://api.robase.dev/v1/otp/verify \
  -H "Authorization: Bearer robe_your_api_key" \
  -H "Content-Type: application/json" \
  -d {"otp_id":"01HXY...","code":"123456"}

# Response
{"status":"verified"}

const res = await fetch("https://api.robase.dev/v1/otp/send", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${apiKey}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    phone_number: "+2348012345678",
    code_length: 6,
    ttl_seconds: 600
  })
});
const { otp_id } = await res.json();

$ch = curl_init("https://api.robase.dev/v1/otp/send");
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => [
        "Authorization: Bearer $api_key",
        "Content-Type: application/json",
    ],
    CURLOPT_POSTFIELDS => json_encode([
        "phone_number" => "+2348012345678",
        "code_length" => 6,
        "ttl_seconds" => 600,
    ]),
]);
$otp_id = json_decode(curl_exec($ch), true)["otp_id"];

body, _ := json.Marshal(map[string]any{
    "phone_number": "+2348012345678",
    "code_length": 6,
    "ttl_seconds": 600,
})
req, _ := http.NewRequest("POST", "https://api.robase.dev/v1/otp/send", bytes.NewReader(body))
req.Header.Set("Authorization", "Bearer "+apiKey)
req.Header.Set("Content-Type", "application/json")
resp, _ := http.DefaultClient.Do(req)

Configurable parameters

Key features to look for in an OTP API

Not all OTP APIs are built for Africa. Use this checklist when evaluating providers.

OTP use cases for African businesses

Across fintech, e-commerce, banking, healthcare, and mobility, SMS OTP is the verification primitive that makes trust possible on a mobile-first continent.

FAQ