In the US, a lot of the communication is done via email and short messages are made via Facebook Messenger, Google Hangouts or Skype (on Computer).
Whereas, in my experience in India, people use Whatsapp or SMS or Facebook Messenger (on phone).
(image stolen from the web)
People in India are not used to detailed messages via email, and prefer short bursts of messages via Whatsapp.
In fact, I had never used Whatsapp in the US and only started using it in India.
Whatsapp is useful to broadcast pics quickly (ala Instagram) and for quick messages (ala SMS), whereas FB Messenger competes with email really.
Thus, there are a lot of differences in how people communicate in the US when compared to India.
The main factor is that people in the US tend to use computers and tablets more and prefer to keep their messengers or whatever open in a browser tab in the background (though with smartphones, that market is rapidly changing), whereas people in India mainly use Smartphones and hence phone programs like Whatsapp tend to be popular.
Another big issue is that people in the US are used to voicemail, and so never really take a phonecall and let it go to voicemail, whereas in our attention-deficit world, people in India have rude interruptions in real life, and scramble to take that call.
Also, there is a difference in talking.
I was used for people to patiently wait for me to finish what I was saying, in the US, but, in India, people interrupt you before you cam finish your sentence, And people assume they know what you are saying and will explain or debate whatever before you can finish saying what you wanted to.