WhatsApp has seemingly begun testing verification methods other than text messages. Users need to verify their number by entering a passcode that is received via SMS on the same number. But WhatsApp has begun testing push notifications that share a passcode on a registered phone in case the account is signed into on a different device. WhatsApp has mentioned in its FAQ page that push notification is meant for account safety when "someone tries to register a WhatsApp account with your phone number." But it could also be a precursor to an upcoming feature that will let users access WhatsApp on concurrent devices.
WhatsApp is now sending push notifications to the user via its app on the registered device when someone else tries to sign in using the same number on a different device. First spotted by folks at WABetaInfo, the feature is working for us as well. However, it is currently available for iOS. Trying to sign in to an Android device while an account is already running on an iPhone will send a push notification on the latter device.
The registration code received via the push notification allows sign-in on a different device. WhatsApp shows a pop-up window inside the app that says: "WhatsApp Registration Code Requested", along with a caution that the code should not be shared with anyone else as it will allow them to access the user's account.
WhatsApp has also noted that it "doesn’t have sufficient information" to identify the individual requesting the registration code. Since the messages are end-to-end encrypted and stored locally, previous conversations cannot be accessed on another device. The cloud backup will also not restore the chats on the second device.
While WhatsApp says it is a security measure that ensures the account is not hacked or compromised by anyone else, it could also pave the way for multi-device support that has been in the anticipation. WABetaInfo had previously reported that WhatsApp could be working on a feature that will allow users to access their account on simultaneous devices. Currently, a user can access WhatsApp on one device at a time. Although, WhatsApp Web can be used to chat on PC devices while an account is accessible via the smartphone app.