Programmable Voice quickstart for Go

Log in to your Twilio account or sign up for a new one.

If you need a Twilio phone number, buy one in the Twilio Console:

1. Go to Phone Numbers > Manage > Buy a Number.
2. Under Capabilities, select Voice.
3. Click Search. The page displays a list of available voice-capable phone numbers.
4. Click Buy next to a phone number to add it to your account.

To check if you have Go installed on your machine, open a terminal and run the following command:

go version

If Go is installed, you should see output similar to:

go version go1.24.4 darwin/arm64

If Go is not installed, install it and open a new terminal window before continuing.

Create a new directory for this project and navigate to it using the command line. Then, create a Go module using the following command:

go mod init voice-quickstart

Install the Twilio Go Helper Library using the following command:

go get github.com/twilio/twilio-go

Create a new file named makecall.go with the following code:

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// Download the helper library from https://www.twilio.com/docs/go/install
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package main
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import (
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	"fmt"
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	"github.com/twilio/twilio-go"
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	api "github.com/twilio/twilio-go/rest/api/v2010"
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	"os"
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)
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func main() {
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	// Find your Account SID and Auth Token at twilio.com/console
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	// and set the environment variables. See http://twil.io/secure
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	// Make sure TWILIO_ACCOUNT_SID and TWILIO_AUTH_TOKEN exists in your environment
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	client := twilio.NewRestClient()
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	params := &api.CreateCallParams{}
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	params.SetUrl("http://demo.twilio.com/docs/voice.xml")
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	params.SetTo("+123456789")
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	params.SetFrom("+19876543210")
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	resp, err := client.Api.CreateCall(params)
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	if err != nil {
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		fmt.Println(err.Error())
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		os.Exit(1)
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	} else {
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		if resp.Sid != nil {
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			fmt.Println(*resp.Sid)
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		} else {
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			fmt.Println(resp.Sid)
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		}
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	}
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}

This code starts a phone call between the two phone numbers that you pass as arguments. The SetFrom number is your Twilio number, and the SetTo number is the number you want to call.

The SetUrl argument points to a TwiML file that tells Twilio what to do when the call recipient answers their phone. This TwiML instructs Twilio to read a message using text-to-speech and then play an MP3.

Replace the SetFrom number with your Twilio phone number, and the SetTo number with your personal phone number. Ensure both numbers are in E.164 format.

Save your changes and run the code:

go run makecall.go

Your phone should ring with a call from your Twilio number. Answer it, and you'll hear a short message.

To handle incoming phone calls, you'll need a web application that can accept HTTP requests from Twilio.

Install the Gin framework by running the following commands:

go get -u github.com/gin-gonic/gin

go mod tidy

Create a file named server.go with the following code:

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package main
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import (
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	"net/http"
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	"github.com/gin-gonic/gin"
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	"github.com/twilio/twilio-go/twiml"
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)
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func main() {
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	router := gin.Default()
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	router.POST("/answer", func(context *gin.Context) {
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		say := &twiml.VoiceSay{
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			Message: "Hello from your pals at Twilio! Have fun.",
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		}
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		twimlResult, err := twiml.Voice([]twiml.Element{say})
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		if err != nil {
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			context.String(http.StatusInternalServerError, err.Error())
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		} else {
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			context.Header("Content-Type", "text/xml")
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			context.String(http.StatusOK, twimlResult)
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		}
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	})
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	router.Run(":1337")
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}

Save the file. Then, start the server with the following command:

go run server.go

If you don't already use ngrok, download and install it.

Open a new command line window or tab and start ngrok with this command:

ngrok http 1337

You should see output similar to:

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Session Status                online                                                                       
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Version                       3.23.2                                                                       
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Web Interface                 http://127.0.0.1:4040                                                        
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Forwarding                    https://ff4660c91380.ngrok.app -> http://localhost:1337                      
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Connections                   ttl     opn     rt1     rt5     p50     p90                                  
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                              0       0       0.00    0.00    0.00    0.00 

1. Go to the Active Numbers page in the Twilio Console.
2. Click your Twilio phone number.
3. Visit the Configure tab and find the Voice Configuration section.
4. In the A call comes in row, select Webhook. In the URL field, enter your ngrok public URL with /answer appended (for example, https://ff4660c91380.ngrok.app/answer).
5. Click Save configuration.

Ensure that ngrok and your Go server are still running.

Make a phone call to your Twilio phone number. Within a few moments, you'll see an HTTP request in your ngrok console, and you'll hear a short message once the call connects.

Now you know the basics of making and responding to phone calls with Go.

This app only used the <Say> TwiML verb to read a message to the caller using text to speech. With different TwiML verbs, you can create other powerful constructs and call flows. Try a few, such as <Record>, <Gather>, and <Conference>.

Let's build something amazing.