Automating Customer Follow Up Messages in Vonage Using SMS API Workflows

If you’re tired of chasing customers with manual follow-ups—or worse, letting them slip through the cracks—this guide is for you. We’ll walk through how to set up automated SMS follow-up messages using Vonage’s SMS API workflows. No fluff, no hand-waving—just the real steps, honest advice, and a few gotchas to watch out for. If you know your way around basic webhooks or APIs but aren’t a professional developer, you’re in the right place.

Why Automate Customer Follow-Ups?

Let’s be real: nobody wants to send the same “Just checking in!” message to 50 people a day. Manual follow-up sucks up time and, frankly, it’s easy to forget. Automating these reminders helps you:

  • Respond to customers quickly, without sounding like a robot.
  • Make sure nobody falls through the cracks.
  • Free up your team for real conversations, not copy-paste jobs.

But—automation can backfire if it’s spammy or impersonal. The trick is to keep it targeted and helpful, not annoying.

What You’ll Need

Before you start, double-check you’ve got these basics covered:

  • A Vonage account with SMS API access (that’s the paid tier—not the free trial, which is too limited for real use).
  • A phone number from Vonage that can send SMS in your target country.
  • Some way to trigger your workflow—this could be a CRM, a database, or just a spreadsheet if you’re scrappy.
  • Basic comfort with APIs or no-code tools (Zapier, Make.com, or similar).

If you’re missing any of these, get those sorted first. This isn’t a magic bullet if the basics aren’t in place.

Step 1: Map Out Your Follow-Up Workflow

Don’t write a line of code yet. Figure out:

  • What triggers a follow-up? (e.g., after a purchase, no reply after 2 days, appointment reminder)
  • How many messages? Just one, or a series?
  • Timing: How long after the trigger do you want to send each message?
  • Message content: Write these out now. Keep it short and clear—nobody wants a novel via SMS.

Pro tip: Avoid “Just checking in…” as your only message. Give a reason to reply, like a useful link or a next step.

Step 2: Set Up Your Vonage SMS API

If you haven’t used Vonage’s SMS API before, here’s the quick version:

  1. Get your API key and secret. Log in to your Vonage dashboard, go to API settings, and copy these down.
  2. Buy a Vonage virtual number. You need this to send SMS. Make sure it matches your customers’ country codes.

  3. Test with a single message. Use a tool like Postman, or curl, to send an SMS to your own phone. Here’s a basic curl example (fill in your info):

    bash curl -X POST https://rest.nexmo.com/sms/json \ -d api_key=YOUR_API_KEY \ -d api_secret=YOUR_API_SECRET \ -d to=YOUR_PHONE_NUMBER \ -d from=YOUR_VONAGE_NUMBER \ -d text="This is a test message"

    If you don’t get the message, double-check your keys, number format (include country code), and check your Vonage account for errors.

Heads up: SMS delivery isn’t 100% guaranteed. Sometimes carriers or spam filters block messages—and Vonage can’t do much about it.

Step 3: Choose Your Workflow Tool

You have three real options here:

1. Build From Scratch (Code Your Own)

  • Best for: Teams with a developer who likes APIs.
  • How: Write a script (Node.js, Python, etc.) that listens for events (like a new row in a Google Sheet, or a webhook from your CRM), waits the right amount of time, then hits the Vonage SMS API.
  • Pros: Total control, endless customization.
  • Cons: You own the bugs, hosting, and security headaches.

2. Use a No-Code Automation Platform

  • Best for: Non-coders, or those who value speed over perfect control.
  • Popular tools: Zapier, Make.com, Pipedream
  • How: Connect your data source (e.g., Google Sheets, CRM) to Vonage using built-in actions or “webhook” steps.
  • Pros: Fast setup, easy to change, no servers.
  • Cons: Monthly fees, not as flexible as custom code, some Vonage features might not be supported out of the box.

3. Hybrid: CRM with Built-in SMS Automation

  • If you already use a CRM (like HubSpot, Salesforce), check if it has Vonage SMS integration or a marketplace app. This is the lowest-maintenance path, though you’ll pay for it.

What to ignore: Fancy “AI” follow-up tools that promise to do everything. They’re often overpriced and deliver generic, awkward messages.

Step 4: Build Your Workflow

Let’s break down what this might look like with each approach.

A. No-Code Example (Zapier)

Say you want to text a customer 24 hours after they fill out a web form.

  1. Trigger: New row in Google Sheets (or new submission in Typeform, etc.).
  2. Delay: Use Zapier’s “Delay” action to wait 24 hours.
  3. Send SMS: Use the “Webhooks by Zapier” action to call Vonage’s SMS API with your customer’s number and your message.

Sample payload for Webhooks by Zapier: - Method: POST - URL: https://rest.nexmo.com/sms/json - Data: - api_key: your API key - api_secret: your API secret - to: customer phone number (with country code) - from: your Vonage number - text: your SMS message

Pro tip: Always test with your own number first. SMS can get expensive if you mess up a loop or send hundreds by accident.

B. DIY Script Example (Python)

If you want more control (or want to send a series of messages), a simple Python script with scheduling (like APScheduler or cron) can do the trick.

Pseudo-code: 1. Fetch list of follow-ups due (from database, file, or CRM export). 2. For each, check if message already sent. 3. If not, call the Vonage API with customer number and message. 4. Log success/failure for each attempt.

Sample using Python and requests:

python import requests

def send_sms(to, text): url = "https://rest.nexmo.com/sms/json" payload = { 'api_key': 'YOUR_API_KEY', 'api_secret': 'YOUR_API_SECRET', 'to': to, 'from': 'YOUR_VONAGE_NUMBER', 'text': text } response = requests.post(url, data=payload) return response.json()

Example usage

send_sms('+12065551234', 'Reminder: Your appointment is tomorrow at 2pm!')

Watch out: Don’t hard-code your API keys in a script you share or store in GitHub. Use environment variables or a secrets manager.

Step 5: Handle Replies & Opt-Outs

Don’t ignore the legal stuff. In most countries, you must offer an opt-out (“Reply STOP to unsubscribe”) and actually honor it.

  • Set up a webhook endpoint in Vonage to receive incoming SMS (replies).
  • When you get a STOP, immediately suppress that number from future sends.
  • If you’re using no-code tools, this may require a workaround or manual process—don’t skip it.

Pro tip: Even if only 2% reply “STOP,” you really don’t want to be on the wrong side of spam complaints or fines.

Step 6: Monitor, Test, and Adjust

Automation isn’t “set it and forget it.” Things to keep an eye on:

  • Delivery reports: Vonage can tell you if messages bounce or fail. Check these in your dashboard or via API.
  • Reply rates: Are people engaging, or just ignoring you?
  • Timing: If people reply “Too late!” or “What is this?”, tweak your timing or message.
  • Costs: SMS isn’t free, and international sends can add up fast.

What doesn’t work: Sending the same message to everyone, or blasting too many at once. You’ll get flagged as spam, and your delivery rates will tank.

Real-World Tips and Honest Warnings

  • Keep messages conversational, not robotic. Pretend you’re texting a friend, not writing a press release.
  • Don’t over-automate. If you find yourself needing 5+ follow-up messages, your sales process probably needs fixing, not more bots.
  • Test with real users. Have a friend or coworker go through the flow and give feedback.
  • Stay legal. SMS rules are strict, especially in the US and EU. Don’t skip the opt-out language.

Wrapping Up

Automated SMS follow-ups in Vonage can be a huge time-saver. But don’t overcomplicate things—start with a single, helpful message and see how it goes. Iterate as you learn what actually works for your customers. Remember: simple, clear, and respectful always beats fancy and annoying. Get your workflow working for you, not the other way around.