this is my first time to upload experiment
simply it is about a sensor ( any type of digital sensor) once its sense the arduino will send a SMS to you with a text

Step 1: What Will You Need ?

you will need:
1_arduino uno or duemilanove (any type could be)
2_ GSM Shield with SIM card
3_a digital sensor ( I used Normaly close switch as a sensor)
***since I used a normally close switch that will effect on the software I wrote it

Step 2: Fix a GSM Shield on the Arduino

put the GSMShield on the arduino that you will use it
and the connect your sensor
the +wire with 5V ,-wire with GND and the signal wire with pin number 8 ( you can use any one from 4 to6 and from 8 to 12) code