In * I use the following to send a SMS message to my mobile phone,  in case of
no answer:

[macro-send_sms_message]
exten => s,1,NoOp(${ARG1})
exten =>
s,n,System(/usr/bin/curl -s "http://localhost/asterisk/sms/sms.php?number=${ARG1}&msg=At%20${ARG3}%20${ARG2}%20called.")


exten => 1200,1,Dial(SIP/1200,10,tT)
exten => 1200,n,Macro(send_sms_message,00324763788xx
,${CALLERID(num)},${STRFTIME(${EPOCH},,%d.%m.%Y-%H:%M)})
.....
.....

This send f.e. the following message:
At 03.08.2008-17:52 00313446413xx called.

How can I do something simular in FS?