I can give a simple suggestion on whatsapp application.
In today’s life whatsapp application very fastly in all over the world. Because it is very useful for every type of person while someone working and using for a job purpose and while someone using whatsapp app just for interacting with friends. Whatsapp launches new feature this month which is video calling. which is also free for everyone on internet and it consume lesser amount of data MBs of internet. And I used this feature it is very helpful.
The video calling never barred in between off calls. this bugs which is very perfectly handled by whatsapp application’s owner and developers.
Whatsapp also have voice call feature which is going from many months. Many people used voice call feature while they dont have balance in their network operator sim and they only have internet.
Whatsapp crossing many billions downloads in just some years. whatsapp is developed by two partners. they have an idea from many years . When they get chance of doing some work on idea. they proved that the idea of their own creativity is very interesting concept and structure. Which becomes very popular in all over the world.