Download
http://44.143.70.8/voipsetup/checkonline.php
http://44.143.70.8/voipsetup/dtmfdecode.php

edit ip in checkonline.php

Add following to manager_custom.conf
[user]
secret = pass
deny=0.0.0.0/0.0.0.0
permit=127.0.0.1/255.255.255.255
read = system,call,log,verbose,command,agent,user
write = system,call,log,verbose,command,agent,user

Add to extension_custom.conf unter [from-internal-custom]
#include hamnet_destination.conf

chmod 777 /etc/asterisk/checkonline.php
add a cron * * * * * /usr/bin/php /etc/asterisk/checkonline.php &> /dev/null