Building an SMS Notification Systemwith API: Complete Guide

const express = require('express');
const Queue   = require('bull');

const smsQueue = new Queue('sms', { redis: { host: 'localhost' } });

// Trigger SMS on order event
app.post('/webhooks/order-placed', async (req, res) => {
  const { phone, orderId, amount } = req.body;

  await smsQueue.add({
    to: phone,
    message: `Order #${orderId} confirmed! Amount: ₹${amount}. Track: https://mystore.in/track/${orderId}`,
    templateId: 'ORDER_CONFIRM_001',
  }, { attempts: 3, backoff: { type: 'exponential', delay: 1000 } });

  res.json({ queued: true });
});

// Queue worker
smsQueue.process(async (job) => {
  const { to, message, templateId } = job.data;
  await sendSMS({ to, message, templateId });
});

import time, requests
from celery import Celery

app = Celery('sms', broker='redis://localhost/0')

@app.task(bind=True, max_retries=3)
def send_notification(self, phone, message, template_id):
    try:
        r = requests.post('https://api.notifytechai.com/v1/sms/send',
            json={'to': phone, 'message': message, 'template_id': template_id},
            headers={'Authorization': f'Bearer {API_KEY}'}, timeout=10)
        r.raise_for_status()

        msg_id = r.json()['message_id']
        track_delivery(msg_id)  # async delivery check
        return {'success': True, 'id': msg_id}

    except Exception as exc:
        delay = 2 ** self.request.retries  # 1s, 2s, 4s
        raise self.retry(exc=exc, countdown=delay)

def track_delivery(message_id, poll_interval=5, max_attempts=12):
    for _ in range(max_attempts):
        r = requests.get(f'.../status/{message_id}', ...)
        status = r.json().get('status')
        if status in ('DELIVERED', 'FAILED'): return status
        time.sleep(poll_interval)

interface SMSProvider { name: string; send: (payload: SMSPayload) => Promise<string>; }

const providers: SMSProvider[] = [
  { name: 'NotifyTech AI', send: notifytechSend },
  { name: 'Fallback-1',  send: fallback1Send  },
];

async function sendWithFallback(payload: SMSPayload): Promise<string> {
  for (const provider of providers) {
    try {
      const msgId = await provider.send(payload);
      console.log(`[SMS] Sent via ${provider.name}: ${msgId}`);
      return msgId;
    } catch (err) {
      console.warn(`[SMS] ${provider.name} failed, trying next...`, err);
    }
  }
  throw new Error('All SMS providers failed — message dead-lettered');
}

// Webhook receiver for delivery status
app.post('/webhooks/sms-delivery', (req, res) => {
  const { messageId, status, timestamp } = req.body;
  updateDeliveryStatus(messageId, status, timestamp);
  res.sendStatus(200);
});