WhatsApp working on multi-phone, tablet chatting. Details here
This is a significant advance from the past when multi-devices could only be run via a desktop client or web browser
Instant messaging app WhatsApp is working on a feature that would let users chat with the same account on multiple phones, or on a phone and a tablet, as per a screen found in a beta version of the app by the site WABetaInfo. The screen gives instructions for registering the device you’re using as a “companion" by scanning a code with your main phone — though currently there doesn’t appear to be an actual code to scan.