A reusable send-SMS function in PHP, Python or Node.js, with timeouts and error handling

The short answer: write one function that sends the SMS and use it everywhere in your system. It takes the number, the text and an event key, reads the API key from an environment variable, has a timeout, always sends an Idempotency-Key and returns the HTTP code and the answer. The retry decision lives in one place: retry with a pause on a 429 or 5xx, never on a 422.

In PHP

function send_sms($number, $text, $event_key) {
$ch = curl_init('https://api.interweb.co.mz/v1/sms/messages');
curl_setopt_array($ch, [
CURLOPT_RETURNTRANSFER => true,
CURLOPT_POST => true,
CURLOPT_TIMEOUT => 30,
CURLOPT_HTTPHEADER => [
'Authorization: Bearer ' . getenv('SMS_API_KEY'),
'Content-Type: application/json',
'Idempotency-Key: ' . $event_key,
],
CURLOPT_POSTFIELDS => json_encode(['number' => $number, 'text' => $text]),
]);
$body = curl_exec($ch);
$http = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
return [$http, json_decode((string) $body, true)];
}

In Python

import os, requests

def send_sms(number, text, event_key):
r = requests.post(
"https://api.interweb.co.mz/v1/sms/messages",
headers={"Authorization": "Bearer " + os.environ["SMS_API_KEY"],
"Idempotency-Key": event_key},
json={"number": number, "text": text},
timeout=30,
)
return r.status_code, r.json()

In Node.js

async function sendSms(number, text, eventKey) {
const r = await fetch("https://api.interweb.co.mz/v1/sms/messages", {
method: "POST",
headers: { "Authorization": "Bearer " + process.env.SMS_API_KEY,
"Content-Type": "application/json",
"Idempotency-Key": eventKey },
body: JSON.stringify({ number: number, text: text }),
signal: AbortSignal.timeout(30000),
});
return [r.status, await r.json()];
}

The event_key is what makes retries safe: something like payment-3381 or order-8812-shipped. With the same value and the same body, the API returns the stored answer instead of sending again.

What to do with the answer