End-to-end encryption and privacy controls.
Message and call for free* around the world.
Group conversations made simple.
Say it with stickers, voice, GIFs and more.
Reach your customers from anywhere.
http://dostan.farafile.ir/file/45912/جزوه-سد-خاکی-پیشرفته--استاد-سروش-(دانشگاه-امیرکبیر)