send sms when destination is down !

hello guys
good time
have you seen windows application or linux application or script to monitor (via icmp ping) and send sms when distination is down ?

attention : my GSM-Modem is USB and I can’t use Serial Model

on PRTG and cacti and another that, you should use serial modem but unfortunatly I havent and I cant buy and i cant use api site.

please provide one solution with USB Modem

now, im using plink.exe
http://forum.mikrotik.com/t/dude-sms-notification-trough-usb-modem-on-ros-from-windows-using-plink/93722/1
and unfortunetly when server is bussy, plink.exe doesnt work and sms doesnt send

can you provide one good solution with USB Modem ?