Which apps are you using to communicate in the US?

Hello guys,
I was just wondering because I wanted some guy to give me his whatsapp number so I can communicate with him on the phone. It often happened to me that especially people in the US don't even use Whatsapp. I can't fking imagine this because in Germany everyone uses whatsapp(even my mom ). SO ye I wanted to ask all of you US residents which apps are u using on a general basis to communicate with friends that everyone owns. I was thinking about iMessage,snapchat,twitter,skype,KiK or facebook messanger?
Would be very thankful for any advice.

When I was living in the US I used to use iMessage and Skype

But I always connects with my partners from US with help of whatsapp.

Skype, You can get them on Skype or Imessege as most often use an iphone.