Make Calls, Send Texts And Register Your Brand For SMS With Twilio

You want to text a customer when their order ships, call them back when a form is submitted, or put a small support desk behind one phone number without buying a phone system. None of that needs a telecoms company. It needs a service that software can ask to make the call or send the text, and that is what Twilio is. Its products are exposed through an API, a way for one program to instruct another, so your booking system, your help desk, a short script or an AI assistant can place a call or send a message on your behalf.

What Twilio does

Twilio is a cloud communications platform providing APIs for SMS, voice, video, and authentication services. Twilio says it is used by over 10 million developers globally, with SDKs for Node.js, Python, Ruby, Java, PHP, C#, and Go. On APIs.io we track 55 separate APIs under the Twilio name, from the ones most people start with, like Calls and Accounts, to narrower ones like Alpha Senders and A2P.

What you can get done

We have mapped Twilio’s operations to 21 business capabilities. These are the four a business will reach for first.

Voice & Telephony

A call placed by software: your system dials the number, plays a message or connects a person, and records how it went. The largest everyday capability, with 51 operations.

• POST /Accounts/{AccountSid}/Calls.json makes an outbound call and tells Twilio what to do when it is answered, including detecting an answering machine.
• GET /Accounts/{AccountSid}/Calls.json lists the calls you have made, filterable to a number, a date or only the ones that failed.
• GET /Accounts/{AccountSid}/Calls/{CallSid}.json reads one call: how long it lasted and how it ended.
• POST /Accounts/{AccountSid}/Calls/{CallSid}.json changes a live call, which is how you hang one up or redirect it mid-call.
• DELETE /Accounts/{AccountSid}/Calls/{CallSid}.json removes an old call from your account’s log.

SMS & Messaging Apps

Before a US business can send text messages through a regular ten-digit number, carriers require it to register as a brand, a process called A2P 10DLC. These operations handle that registration, and let your texts show a brand name instead of a number where that is allowed. There are 11 operations.

• POST /v1/a2p/BrandRegistrations registers your business as a brand so you can send texts in the US.
• GET /v1/a2p/BrandRegistrations/{Sid} checks the approval status of a registration, and why one was rejected.
• POST /v1/a2p/BrandRegistrations/{Sid} pushes a failed registration back through review after you fix your profile.
• POST /Services/{ServiceSid}/AlphaSenders adds an alphanumeric sender ID, so messages arrive from your brand name.
• GET /Services/{ServiceSid}/AlphaSenders lists the sender IDs attached to a messaging service.

Contact Centre Operations Management

Flex is Twilio’s contact centre product. A Flex Flow decides how an inbound contact reaches an agent, and a channel is one customer conversation in progress. This is the biggest capability by operation count, with 79 operations.

• POST /FlexFlows routes a new inbound channel into Flex, handing contacts to a workflow.
• GET /FlexFlows lists the flows that decide how inbound contacts reach your agents.
• POST /FlexFlows/{FlexFlowSid} switches a flow to a different setup, or disables it without deleting it.
• POST /Channels starts a new chat channel when a customer reaches out, with any pre-engagement data.
• DELETE /Channels/{ChannelSid} removes a channel once the conversation is over.

Telecom Regulatory Compliance Management

Many countries require identity and address documents before you can buy a phone number there. Twilio groups those documents into a regulatory bundle that goes for review. These operations, 31 in all, let software file and track the bundles.

• POST /v2/RegulatoryCompliance/Bundles starts a bundle for the country and number type you need.
• GET /v2/RegulatoryCompliance/Bundles lists your bundles, including the ones still waiting on review or rejected.
• POST /v2/RegulatoryCompliance/Bundles/{Sid} submits a draft bundle for review once it is complete.
• POST /v2/RegulatoryCompliance/Bundles/{BundleSid}/Copies duplicates an approved bundle, documents included, as the starting point for a new one.

Workflows that put it together

A workflow is a recipe: several API calls made in a set order, each using what the last one returned. They are written in Arazzo, an open format for describing them, and Twilio has 28 of them on APIs.io.

• Look Up a Phone Number fetches the carrier, line type and caller name for a number before you use it.
• Create a Conversation, Add a Participant, and Send a Message stands up a thread, attaches an SMS participant and posts the first message.
• Reply to a Conversation and Track Delivery Receipts posts a reply and then lists the delivery receipts for it.
• Inspect a Call and Hang It Up If Live fetches a call and ends it if it is still in progress.
• Find an In-Progress Conference and Add a Participant finds a running conference and dials someone new into it.

Ask for it in plain language

We have written conversational overlays for Twilio, a layer on top of its API descriptions that maps everyday questions to the operation that answers them, so an AI assistant knows which call to make. There are 115 of them, one per API. These are the kinds of questions they map:

• “How do I make an outbound phone call and control what happens when it is answered?”
• “Which calls did we place to a particular phone number last month?”
• “How do I register my business as a brand before sending 10DLC texts in the US?”
• “How do I send SMS that shows my brand name instead of a phone number?”
• “Which of my regulatory bundles are still waiting on review or were rejected?”
• “How do I route a new inbound contact channel into Flex?”

You can see one of them on the A2P API phrasing overlay.

Getting started

Twilio is a paid, hosted service: you call their endpoint, and you pay for what you send and the numbers you hold. The documentation is organised by product, and the Account API page is where credentials begin. On APIs.io you can browse the Twilio profile, the Calls API, the A2P API and the Alpha Senders API. If you are in the US and texting is the goal, start with the brand registration, because everything else waits on it.