What Is Twilio? Adding SMS and Voice to Your Business Automations
A plain-English intro to Twilio — what it does, why SMS is still the most effective customer communication channel, and how it fits into your automation stack.
Here’s a question I get asked a lot: why bother with SMS? Email exists. Push notifications exist. Why add another communication tool to the stack?
The answer is simple. SMS messages get read. Email doesn’t.
When I built SendJob, I needed a way to tell customers that their technician was on the way, that the job was complete, and that their payment was processed. I tried email-only first. The engagement was poor. Customers would miss the job arrival notification entirely and then call to complain the tech showed up unannounced. The switch to SMS changed everything. Open rates went from under 25% to effectively 100%.
Twilio is how I made that happen. And it’s become one of the most important tools in the stack.
What Twilio Is
Twilio is a cloud communications platform. That’s the broad definition — let me make it concrete.
For business owners: Twilio is the infrastructure behind every appointment reminder, job status text, two-factor login code, and automated follow-up SMS you’ve ever received from a modern business. When your phone buzzes with a message from a company you hired — and it actually shows up on time with the right information — there’s a very good chance Twilio is involved on the back end. Twilio is why automated messages actually reach real phone numbers on every carrier.
For builders: Twilio is a REST API for communications. Send an SMS with an HTTP POST request. Make a phone call. Send MMS with an image attachment. Start a WhatsApp conversation. Send a verification code for 2FA. Receive inbound messages and route them to your application logic. All of it accessible via API, all of it documented clearly, and all of it with an n8n native integration that makes setup quick.
The core products you’ll use in a field service automation stack:
- Messaging — SMS and MMS, the workhorse
- Voice — programmatic phone calls (less common in automation stacks, but powerful)
- Verify — one-time codes for two-factor authentication
- WhatsApp API — for markets where WhatsApp is the primary messaging channel
For SendJob and most US-based business automation, Messaging is what you’ll use the most.
Why SMS Still Wins for Business Communications
I want to address this directly because the question comes up every time I talk about adding Twilio to a stack.
Email open rates average 20–30% for business communications. SMS open rates average 98%, with the majority of messages read within three minutes of delivery. Those are not comparable numbers.
For time-sensitive, action-required communications, that gap is the difference between a well-functioning business and constant customer service problems.
Think about the communications in a field service job:
- Appointment confirmation
- Day-before reminder
- Technician assigned notification
- Technician on the way (with ETA)
- Technician arrived
- Job complete
- Payment link
Every single one of those is time-sensitive. If the customer misses the “technician on the way” text because it went to their spam folder or they didn’t check email for three hours, you get a complaint. You get a door knock with no one home. You get a negative review about communication.
SMS eliminates those failure modes. The message arrives. It gets read. The customer responds or acts appropriately. This is not a marginal improvement — it’s a fundamental change in how reliably your business operates.
Voice calls are not an equivalent substitute. Many people don’t answer calls from unknown numbers. Voicemails don’t get returned. SMS has none of those friction points.
How SendJob Uses Twilio
There are seven SMS touchpoints in a typical SendJob job lifecycle. All of them go through Twilio.
- Job confirmation — Customer books, immediately receives a confirmation with the job details and a reference number
- Technician assigned — When a tech accepts the job, the customer gets a message with the tech’s name and a rough arrival window
- Tech accepted — The dispatching team is notified that the tech confirmed the assignment
- Enroute with ETA — When the tech marks themselves as en route, the customer gets their ETA and the tech’s name
- Onsite arrival — When the tech checks in at the job address, the customer gets a “your tech has arrived” message
- Job complete — Customer receives a completion confirmation
- Payment link — Customer receives a Twilio SMS with a link to pay the invoice
Without Twilio, SendJob doesn’t exist as a product. The entire value proposition — customers always know what’s happening, dispatching is automated, technicians don’t have to make calls to customers — depends on these messages going out reliably and on time.
That’s 7 SMS messages per job. At 100 jobs per month, that’s 700 messages. At 1,000 jobs per month, that’s 7,000. Twilio handles all of it without configuration changes.
Where Twilio Fits in the Stack
Twilio is the outbound voice of your automation system. It’s the mechanism by which decisions made in n8n — “this job just changed to enroute, send the ETA text” — get communicated to real people on their real phones.
Here’s how the roles divide:
- Supabase holds the customer phone number, job status, and all the data
- n8n detects when something worth communicating has happened (via schedule, webhook, or database trigger)
- Twilio makes the actual delivery happen — reaching the customer’s phone
Twilio doesn’t decide when to send. It doesn’t know what triggered the message. It just receives an instruction from n8n and executes: send this message body, from this number, to this recipient.
But the relationship isn’t one-directional. Twilio can also receive. When a customer replies to an SMS, Twilio captures that reply and fires a webhook back to n8n. When a message is delivered (or fails), Twilio fires a delivery status webhook. Your system can respond to both — confirming receipt, updating job records, handling opt-outs — because Twilio is a two-way communication layer.
How Twilio Connects to Everything
n8n → Twilio (outbound SMS): n8n has a native Twilio node. Set up the credential once with your Account SID and Auth Token, then any workflow can send an SMS by connecting to the Twilio node and filling in the To number, From number, and message body. No API documentation required.
Twilio → n8n (delivery status): Configure your Twilio phone number to POST a delivery status webhook to an n8n webhook URL whenever a message is delivered, fails, or is undelivered. n8n receives the payload, parses the status, and updates the delivery record in Supabase. You end up with a complete log showing exactly which messages reached customers and which didn’t.
Twilio → n8n (inbound SMS): When a customer replies to your SMS, Twilio fires a webhook to n8n containing the message body and the sender’s phone number. n8n can route the reply — check if it says “YES” and confirm an appointment, check if it says “STOP” and mark the customer as opted out, or pass the text to an AI node for more complex intent detection.
n8n → Supabase → n8n → Twilio: The full chain for an event-driven SMS: a job status changes in Supabase → Supabase Database Webhook fires to n8n → n8n queries the customer’s phone number from Supabase → n8n calls Twilio → Twilio delivers the SMS. This entire sequence takes about 2–3 seconds end to end.
Twilio vs the Alternatives
Let me be direct: Twilio costs more than some alternatives. Here’s how it stacks up.
Vonage (formerly Nexmo): Similar capabilities to Twilio. Slightly lower prices in some regions, particularly Europe. Smaller developer community and ecosystem. The documentation and n8n integration are not as mature. A reasonable choice if you’re heavily EU-focused and price-sensitive.
Plivo: Competitive pricing, often cheaper than Twilio per message. Solid reliability. Smaller integration ecosystem and weaker developer experience than Twilio. A legitimate option if cost is your primary constraint and you’re comfortable doing more manual setup.
Bandwidth: Carrier-grade infrastructure used by large enterprises. Designed for very high volumes. More complex to integrate, less suited for small-to-medium automations. Not the right starting point.
Sinch: Strong European and Latin American coverage. Growing developer ecosystem. Less mature than Twilio in terms of documentation and third-party integrations.
AWS SNS (for SMS only): Extremely cheap — often under half the price of Twilio. But the developer experience is genuinely bad. No phone number management, no delivery receipts in the same format, no inbound messaging without significant extra configuration. Fine for one-way bulk notifications at very high volume. Not what you want for a real two-way automation stack.
My honest recommendation: start with Twilio. The documentation is the best in the industry — genuinely useful, well-organized, full of working examples. The reliability is excellent. n8n has a native integration that works without configuration headaches. And at the volumes most small-to-medium businesses operate at, the price difference versus alternatives is a few dollars per month — not worth the friction of using a platform with worse tooling.
Revisit alternatives if you’re sending at very high volume (tens of thousands of messages per month) and the cost difference becomes meaningful.
What Twilio Costs
Twilio has no monthly subscription fee. You pay for what you use.
SMS pricing (US):
- Outbound SMS: ~$0.0079 per message (less than a penny)
- Inbound SMS: ~$0.0075 per message
- MMS (with image): ~$0.0200 per message
Phone numbers:
- Local 10-digit number: $1.15/month
- Toll-free number: $2.15/month
- Short code: $500–$1,000/month (for very high volume — you don’t need this to start)
Free trial: Twilio gives you $15 in credit when you sign up. With trial credits, you can only send to phone numbers you’ve verified in the console (a restriction removed when you upgrade to a paid account). The free trial is enough to build and test a complete workflow.
At SendJob volumes — roughly 7 SMS per job, 100 jobs per month — that’s about 700 messages totaling approximately $5.50 in SMS charges, plus $1.15 for the phone number. Call it $7/month. At 500 jobs per month, it’s closer to $30/month. The economics of SMS are very friendly at small-to-medium scale.
What the Series Covers Next
Twilio Basics gets you operational:
- Setting up your account and getting a phone number
- Understanding the Twilio console and where to find your credentials
- The #1 beginner mistake (phone number formatting — it will break your workflow)
- Connecting to n8n and sending your first SMS
- Understanding delivery statuses
Twilio Advanced goes deeper:
- Status callbacks — tracking whether your messages actually delivered
- Receiving inbound SMS and processing replies
- Building a full two-way messaging flow
- Handling opt-outs and TCPA compliance
- A2P 10DLC registration (required for sending at any real scale in the US)
- Debugging failed messages
Ready to send your first text? Getting Started with Twilio →