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.

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.

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.

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, navigate to the Resources tab in your SignalWire Dashboard, click + Add New, and select SWML Script.

1
version: 1.0.0
2
sections:
3
  main:
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    - 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"
>
  }
>
}'

Next steps

SWML 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, check out the SDKs for programmatic call handling.