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Sending an SMS from FreeSWITCH XML Dialplan

In order to send an SMS from a FreeSWITCH dialplan extension, we need to do a few things:

  1. Fill out the space_name, project_key, api_token, signalwire_number, and cellphone channel variables.

  2. Substitute all the spaces in the sms_body for the url encoded equivalent of %20:
    sms_body=${system(printf 'aleg ${uuid} is calling bleg ${bleg_uuid}' | sed -r 's/ /%20/g')}

  3. Calculate the base64 equivalent of your authorization credentials so auth is properly setup for curl header append_headers Authorization:'basic ${auth}':

auth=${system(printf '${project_key}:${api_token}' | base64 --wrap 0)

  1. Then, you have the Dialplan Extension. Dial 792 from any registered sip phone, or from bash do: fs_cli -x 'originate loopback/792 echo inline'. Then, your cellphone should receive a text. Review the comments in the extension for additional notes.
<extension name="signalwire sms curl">
      <condition field="destination_number" expression="^792$">

        <!-- setup bleg uuid of this call so we we know it before hand -->
        <action application="set" inline="true" data="bleg_uuid=${create_uuid()}"/>

        <!-- setup signalwire credentials -->
        <action application="set" inline="true" data="space_name=XXXXXX"/>
        <action application="set" inline="true" data="project_key=XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXX"/>
        <action application="set" inline="true" data="api_token=PTXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"/>

        <!-- not using '+' here, just the 11 digit number itself, see curl line below -->
        <action application="set" inline="true" data="signalwire_number=1XXXXXXXXXX"/>
        <action application="set" inline="true" data="cellphone=1XXXXXXXXXX"/>

        <!-- urlencode your 'spaces' to '%20' so the text body will work in the url, may need to consider other untested puncuations -->
        <action application="set" inline="true" data="sms_body=${system(printf 'aleg ${uuid} is calling bleg ${bleg_uuid}' | sed -r 's/ /%20/g')}"/>

        <!-- We need to base64 encode the basic authorization -->
        <action application="set" inline="true" data="auth=${system(printf '${project_key}:${api_token}' | base64 --wrap 0)}"/>

        <!-- notice for E.164 formatting we encode the '+' to '%2B' for the 'From' and 'To' params on the URL -->
        <action application="curl" data="https://${space_name}.signalwire.com/api/laml/2010-04-01/Accounts/${project_key}/Messages.json?From=%2B${signalwire_number}&To=%2B${cellphone}&Body=${sms_body} append_headers Authorization:'basic ${auth}' post"/>

        <action application="hangup"/>
      </condition>
    </extension>

From this example, your cellphone should receive an SMS that looks like this:

​​​​​​​aleg 0739c067-c8b3-4a1d-bc8d-76f4a7e71c55 is calling bleg 426cd62b-fbcf-4fb2-a10a-9226dff5ac5d