[Q] efs folder

Hi,

I am trying to follow a tutorial to install a new custom rom on my android phone.

My phone is a Samsung Ace GT-S5830

In this tutorial they recommand to make a backup of the efs folder.

My phone is already rooted and a old friend of mine installed a custom rom.

But I can't found this folder on my phone but my phone works fine for the network signal.

Is it possible?
Is there a way to found this folder?

Thanks for your response.