Lua send SMS via Flowroute when a voicemail is left

Posted on August 23, 2016 by Flowroute

By Steven Schoch, originally published by FreeSwitch.


Assuming Lua is already installed on your system and configured with FreeSwitch.

If you don’t have an account with, sign up and enable the developer account needed. At the current time, this can be found under Preferences > API control.

You may need to visit to setup the credentials. You will also need to purchase a DID from Flowroute so you can actually send SMS messages.

Here’s the script that does the actual processing. As you may have guessed, load this to /usr/local/freeswitch/scripts and read below for the rest of the configuration needed. Add your user and password in the url section.


     This script is called by configuration inautoload_configs/lua.conf.xml.
     It is called on a "vm:maintenance"event.
-- The following is specifc to the Flowroute SMS API,
-- documented at
url = ""
action = event:getHeader("VM-Action")
ifaction ~= "leave-message"thenreturnend
user = event:getHeader("VM-User")
domain = event:getHeader("VM-Domain")
caller_id_name = event:getHeader("VM-Caller-ID-Name")
caller_id_number = event:getHeader("VM-Caller-ID-Number")
--[[ We don't care about these:
file_path = event:getHeader("VM-File-Path")
flags = event:getHeader("VM-Flags")
folder = event:getHeader("VM-Folder")
uuid = event:getHeader("VM-UUID")
message_len = event:getHeader("VM-Message-Len")
timestamp = event:getHeader("VM-Timestamp")
api = freeswitch.API();
from = api:execute("user_data", user .. "@".. domain ..  " var outbound_caller_id_number")
to = api:execute("user_data", user .. "@".. domain .. " param vm-notify-sms")
ifto == ""thenreturnend
ifcaller_id_name == ''
        or caller_id_name == 'UNKNOWN'
        or caller_id_name == 'UNASSIGNED'
        or caller_id_name == 'WIRELESS CALLER'
        or caller_id_name == 'TOLL FREE CALL'
        or caller_id_name == 'Anonymous'
        or caller_id_name == 'Unavailable'
        thencaller_id_name = nil end
ifcaller_id_number == ''
        thencaller_id_number = nil end
message = "Voicemail "
        thenmessage = message .. "from ".. caller_id_name .. " ("..  caller_id_number .. ")"
        elseif caller_id_number
        thenmessage = message .. "from ".. caller_id_number end
message = message .. " at ".."%a %H:%M", timestamp)
message = message .. " length ".. message_len .. " seconds"
message = message .. " to box ".. user
message = message .. "."
-- Add JSON string escapes to the message
message = string.gsub(message, "([\\\"'])", "\\%1")
-- Send the text
data = '{ "to": "'.. to .. '", "from": "'.. from .. '", "body": "'.. message .. '"}'
api:execute("curl", url .. " content-type application/json post '".. data .. "'")


Edit /usr/src/freeswitch/modules.conf and enable applications/curl:



Compile FreeSwitch as usual:

Build FreeSWITCH
# Or if you're following master:


Now you will need to have mod_curl load when you start FreeSwitch. Edit /usr/local/freeswitch/conf/autoload_configs/modules.conf.xml:

<load module="mod_curl"/>

Uncomment mod_curl and make it look like the above.


Add the line below to your extension, such as /usr/local/freeswitch/conf/directory/default/1001.xml:

<param name="vm-notify-sms"value="1202478xxxx"/>

Be sure to add this within the <params> tag and not <variables>.

This will be the telephone number where you want to receive the alert. Replace it with a legitimate phone number.


In the same file, you will need to consider adding your Flowroute number that you purchased. You must send from a Flowroute phone number that’s associated with your account.

Caller ID
<variable name="outbound_caller_id_number"value="1468856xxxx"/>

You can also edit /usr/local/freeswitch/conf/vars.xml and have a global caller ID, if desired.


Add this line to /usr/local/freeswitch/conf/autoload_configs/lua.conf.xml:

<hook event="CUSTOM"subclass="vm::maintenance"script="voicemail-event.lua"/>

Ensure this is somewhere between the beginning and ending <settings> tags.



fs_cli to the Freeswitch server, make a call and look for something like this after the voicemail is processed:

2016-07-01 04:48:02.930006 [DEBUG] mod_lua.cpp:459 lua event hook: execute ‘voicemail-event.lua’


Check the device the SMS was sent to and you’ll see a message like the following:

Voicemail from Extension 1000 (1000) at Fri 04:48 length 6 seconds to box 1001.