How to get the best out of this forum - Using Arduino / Project Guidance - Arduino Forum
"We" are a help-forum, not a code writing consortium.
Post all of your code you have developed and do so within the </> tool on the menu.
Tell us the model of GSM with a link to device purchased
Tell us which Arduino board you are using
What model of photosensor do you use
Anything else specific to your project will benefit the forum to assist.