Send WhatsApp Messages with Twilio – Complete 2025 Guide

Send WhatsApp Messages with Twilio – Complete 2025 Guide

Twilio’s WhatsApp Business API lets any developer or small business deliver appointment reminders, dispatch alerts or boarding passes straight to a customer’s WhatsApp inbox. The set-up is shorter than a coffee break and costs less than a London bus fare.

What You Need Before You Start

• A Twilio account (free trial gives you £12 credit – enough for roughly 1,200 UK WhatsApp messages)
• A mobile phone with WhatsApp installed (for testing)
• Python 3.9+ or Node.js 18+ (examples below use Python)

Step 1 – Activate the WhatsApp Sandbox

1. Log in to console.twilio.com
2. Choose “Explore Products” → “Messaging” → “Try WhatsApp”
3. Copy the **sandbox number** (it looks like +1 415 523 8886) and the **join code** (e.g., join abc123)
4. Open WhatsApp on your phone, send the join code to the sandbox number – this pairs your handset for testing

Step 2 – Grab Your Credentials

Still in the console, note:

• Account SID (starts AC…)
• Auth Token (keep this private)

Store them as environment variables so you never hard-code keys:

export TWILIO_ACCOUNT_SID=ACxxxxxxxxxxxxxxxxxxx
export TWILIO_AUTH_TOKEN=your_auth_token

Step 3 – Install Twilio’s Helper Library

pip install twilio

Step 4 – Send Your First Message

Create send_whatsapp.py and paste:

import os
from twilio.rest import Client
account_sid = os.environ["TWILIO_ACCOUNT_SID"]
auth_token  = os.environ["TWILIO_AUTH_TOKEN"]
client = Client(account_sid, auth_token)
message = client.messages.create(
from_="whatsapp:+14155238886",  # sandbox number
to="whatsapp:+447700900123",     # your phone in E.164
body="Hello from Twilio and husham.com!"
)
print(f"Message sent: {message.sid}")

Run:

python send_whatsapp.py

Your phone should receive the text within seconds.

Step 5 – Using a Template (Business-Initiated)

Outside the 24-hour “customer care window” you must use a Twilio-approved template. In the console:

1. “Messaging” → “Templates” → “Create a new template”
2. Example: Your appointment is on {{1}} at {{2}}.
3. Submit for WhatsApp approval (usually 2–4 minutes in 2025)

Once approved, swap the body for a content_sid call:

message = client.messages.create(
        from_="whatsapp:+14155238886",
        to="whatsapp:+447700900123",
        content_sid="HXb5b62575e6e4ff6129ad7c8efe1f983e",
        content_variables='{"1":"22 July 2026","2":"3:15pm"}'
      )

Pricing Quick View (October 2025)

• UK – 4.2 p per outbound template message
• UK – 2.1 p per outbound “session” message (inside 24-hour window)
• Incoming messages are free
• No monthly fee; you only pay for what you send

Common Pitfalls

• Wrong prefix – always use whatsapp: before the number
• Non-E.164 – UK mobiles must start +447, not 07
• Template outside window – WhatsApp will reject free-form text after 24 hours

Going Live (Next Steps)

1. Buy a real Twilio number (£1/month)
2. Complete Facebook Business verification (WhatsApp owns the pipes)
3. Submit your display name for approval (24-hour SLA)
4. Replace the sandbox number with your own in the code

Bottom Line

With a single API call you can reach customers where open rates exceed 90%. Twilio’s pay-as-you-go model keeps costs predictable, and the sandbox lets you prototype for free. For real-world gotchas, template ideas or billing hacks, jump into the husham.com forum – the thread is updated every time WhatsApp tweaks its policy.

Pricing & policy accurate: 28 October 2025