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Making and receiving phone calls

Follow this guide to make and receive your first phone calls using SignalWire Markup Language (SWML) and the SignalWire API.

We'll also show you how to accomplish the same goals using cXML and the Compatibility API, which are ideal for migrating existing Twilio applications to SignalWire.

Prerequisites​

To be able to make calls, you will need:

  • a SignalWire phone number
  • your API credentials (Space URL, Project ID, and API token)

Also, note that if your account is in trial mode, you'll need to upgrade it in order to call numbers other than your own verified numbers. See How to exit Trial Mode.

To acquire a phone number, log in to your SignalWire Space. From the Phone Numbers section, buy a new phone number. You will need at least one number to make and receive calls.

Find your API tokens in the API section of your Space, as shown below. You may need to create a new token if you never used one. Make sure that your token has at least the "Voice" scope enabled.

The API page.

You can find your Project ID and Token from the API tab in your SignalWire Space. Make sure your token has the 'Voice' scope enabled.

Identify your Dashboard and select between Legacy and New UIs using the tabs below.

The main sidebar menu of the new SignalWire Space Dashboard UI.

The redesigned main menu.

The selection menu when a new Resource is created.

The new SignalWire Dashboard features a streamlined sidebar menu. Many items are now located in the unified My Resources menu.

Resources that were previously accessible in the sidebar of the legacy UI are now located in the unified My Resources menu.

SWML​

Receiving incoming calls​

To handle incoming calls we need to configure the phone number in our SignalWire Space to answer calls using a SWML Script.

To create a SWML Script in the new UI, go to the Resources section from the sidebar, and create a new Resource. In the new resource picker, select Script and create a SWML Application.

Attach Phone Number
version: 1.0.0
sections:
  main:
    - play: say:Hello from SignalWire!

Take note of the Request URL for the SWML Script that we created. You can even create a new script if you want to define a different behavior for incoming calls.

To configure your number to handle incoming calls with an SWML Script, click the Phone Numbers section within your SignalWire Space, and edit the settings of the specific number you would like to use to answer calls. Set Handle calls using to a SWML Script, then select your SWML Script from the dropdown

That's it! Inbound calls to this SignalWire number will execute the specified SWML Script.

Making your first call​

Outbound calls can be made via the SignalWire REST API's Create a Call endpoint. This is accomplished by sending a POST request using SWML in the request body to handle the call. The SWML can be served via URL or passed inline directly as an escaped JSON string.

curl -L -g 'https://Your_Space_Name.signalwire.com/api/calling/calls' \
-H 'Content-Type: application/json' \
-H 'Accept: application/json' \
-H "Authorization: Basic $(echo -n "${YOUR-PROJECT-ID}:${YOUR-API-TOKEN}" | base64)" \
--data-raw '{
  "command": "dial",
  "params": {
    "from": "sip:from-sip@example-112233445566.sip.signalwire.com",
    "to": "+1xxxxxxxxxx",
    "caller_id": "+1234567890",
    "fallback_url": "https://example.com/fallback",
    "status_url": "https://example.com/status_callback",
    "status_events": [
      "answered",
      "ended"
    ],
    "url": "https://example.com/swml"
  }
}'

Compatibility API​

The Compatibility API is built to enable easy migration from the Twilio REST API. Likewise, cXML is built for compatibility with TwiML.

info

If you're starting a new application from scratch, we recommend you follow the SWML (SignalWire Markup Language) instructions instead.

To handle incoming calls we need to configure the phone number in our SignalWire Space to answer calls using a cXML resource.

If you're on the new UI, go to the Resources section from the sidebar, and create a new Resource. In the new resource picker, select Script and create a cXML script.

Attach Phone Number

Utilize the following cXML which uses the <Say> verb to play a text-to-speech message:

<?xml version="1.0" encoding="UTF-8"?>
<Response>
  <Say>Welcome to SignalWire. This is my first call.</Say>
</Response>

Go to the Phone Numbers section from the sidebar, and edit the phone number you want to answer calls with. From there, click on the Assign Resource button for incoming calls, and select the newly created cXML script to connect.

Attach Resource

To call a number via cXML you can make a POST request to the Compatibility REST API's Create a Call endpoint.

curl -L -X POST 'https://{SpaceName}.signalwire.com/api/laml/2010-04-01/Accounts/{ProjectID}/Calls' \
  -H 'Content-Type: application/x-www-form-urlencoded' \
  -H 'Accept: application/json' \
  -u '{ProjectID}:{APIToken}' \
  --data-urlencode 'Url=https://{BinRequestURL}' \
  --data-urlencode 'From={+XXXXXXXXXX}' \
  --data-urlencode 'To={+YYYYYYYYYY}'

Make sure to replace all occurrences of {SpaceName}, {ProjectID}, {APIToken}, {BinRequestURL}, {+XXXXXXXXXX}, and {+YYYYYYYYYY} with your actual values.

In order to locate the {BinRequestURL}, navigate to your cXML script and copy the Request URL that is present.

note

Instead of your own bin, feel free to try one of ours: <https://<spacename>.signalwire.com/laml-bins/f85376be-7fe1-439b-a24f-3113ff980804>.

Congratulations! Once the cURL request is executed, your personal phone number ({+YYYYYYYYYY}) will start ringing.

Next steps​

SWML and cXML scripts allow you to handle incoming phone calls, and REST APIs make it easy to trigger outbound calls.

If you need more flexibility and real-time control on your calls, you may be interested in our guide about how to make and receive calls in Node.js.